2 minutes read (About 290 words)

How to stitch and sort array in Swift

Issue #672

Supposed we want to stitch magazines array into books array. The requirement is to sort them by publishedDate, but must keep preferredOrder of books. One way to solve this is to declare an enum to hold all possible cases, and then do a sort that check every possible combination 

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struct Book {
    let preferredOrder: Int
    let publishedDate: Date
}

struct Magazine {
    let publishedDate: Date
}

enum StitchItem {
    case book(Book)
    case magazine(Magazine)
}

func stitch(_ books: [Book], magazines: [Magazine]) -> [StitchItem] {
    let items = books.map({ StitchItem.book($0) }) + magazines.map({ StitchItem.magazine($0) })
    return items.sorted(by: { book, magazine in
        switch (book, magazine) {
        case let (.book(b1), .book(b2)):
            return b1.preferredOrder < b2.preferredOrder
        case let (.book(book), .magazine(magazine)):
            if book.publishedDate == magazine.publishedDate {
                return true
            } else {
                return book.publishedDate < magazine.publishedDate
            }
        case let (.magazine(magazine), .book(book)):
            if book.publishedDate == magazine.publishedDate {
                return false
            } else {
                return book.publishedDate < magazine.publishedDate
            }
        case let (.magazine(m1), .magazine(m2)):
            return m1.publishedDate < m2.publishedDate
        }
    })
}

The above sort function declares the intention but Swift just sort instead of trying to fully meet our requirements.

A manual solution is to sort each array first then use while loop to insert.

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func stitch(_ books: [Book], magazines: [Magazine]) -> [StitchItem] {
    let books = books
        .sorted(by: { $0.preferredOrder < $1.preferredOrder })
    let magazines = magazines
        .sorted(by: sortmagazines)

    var bookIndex = 0
    var magazineIndex = 0
    var results: [StitchItem] = []
    while (bookIndex < books.count && magazineIndex < magazines.count) {
        let book = books[bookIndex]
        let magazine = magazines[magazineIndex]
        if book.publishedDate < magazine.publishedDate {
            results.append(StitchItem.book(book))
            bookIndex += 1
        } else {
            results.append(StitchItem.magazine(magazine))
            magazineIndex += 1
        }
    }

    while (bookIndex < books.count) {
        let book = books[bookIndex]
        results.append(StitchItem.book(book))
        bookIndex += 1
    }

    while (magazineIndex < magazines.count) {
        let magazine = magazines[magazineIndex]
        results.append(StitchItem.magazine(magazine))
        magazineIndex += 1
    }

    return results
}
a minute read (About 120 words)

How to make dynamic font size for UIButton

Issue #671

Use adjustsFontForContentSizeCategory

A Boolean that indicates whether the object automatically updates its font when the device’s content size category changes.

If you set this property to YES, the element adjusts for a new content size category on a UIContentSizeCategoryDidChangeNotification.

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button.titleLabel?.adjustsFontForContentSizeCategory = true
button.backgroundColor = UIColor.green
button.titleLabel?.font = UIFont.preferredFont(forTextStyle: .title1)

label.adjustsFontForContentSizeCategory = true
label.backgroundColor = UIColor.yellow
label.font = UIFont.preferredFont(forTextStyle: .title1)

However it seems view (UIButton or UILabel) size is the same, just the inner text increases in size. A workaround is to put view inside UIStackView so UIButton or UILabel can automatically changes size.

a few seconds read (About 92 words)

How to test for view disappear in navigation controller

Issue #670

To test for viewWillDisappear during UINavigationController popViewController in unit test, we need to simulate UIWindow so view appearance works.

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final class PopTests: XCTestCase {
    func testPop() {
        let window = UIWindow(frame: UIScreen.main.bounds)
        let navigationController = UINavigationController()
        window.rootViewController = navigationController
        let viewController = DetailViewController()

        navigationController.viewControllers = [
            UIViewController(),
            viewController
        ]

        window.makeKeyAndVisible()
        let expectation = XCTestExpectation()
        navigationController.popViewController(animated: false)
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
            XCTAssertTrue(viewController.wasDismissed)
            expectation.fulfill()
        }
        wait(for: [expectation], timeout: 1)
    }
}
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class DetailViewController: UIViewController {
        override func viewWillDisappear(_ animated: Bool) {
            super.viewWillDisappear(animated)
            if isMovingFromParent {
                wasDismissed = true
            }
        }
}
a few seconds read (About 27 words)

How to set text color for UIDatePicker

Issue #660

Apply tintColor does not seem to have effect.

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datePicker.setValue(UIColor.label, forKeyPath: "textColor")
datePicker.setValue(false, forKey: "highlightsToday")
2 minutes read (About 243 words)

How to make switch statement in SwiftUI

Issue #656

Lately I’ve been challenging myself to declare switch statement in SwiftUI, or in a more generalized way, execute any anonymous function that can return a View

Use Switch and Case views

Note that this approach does not work yet, as TupeView should support variadic number of contents, and also T.RawValue needs to conform to Equatable in order to check the cases.

Also in Switch statement, Content can’t be inferred

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struct Case<T: RawRepresentable, Content: View>: View {
    let value: T
    let content: Content

    init(_ value: T, @ViewBuilder content: () -> Content) {
        self.value = value
        self.content = content()
    }

    var body: some View {
        content
    }
}

struct Switch<T: RawRepresentable, Content: View>: View {
    let value: T
    let cases: TupleView<Case<T, Content>>

    init(_ value: T, @ViewBuilder cases: () -> TupleView<Case<T, Content>>) {
        self.value = value
        self.cases = cases()
    }

    var body: some View {
        makeBody()
    }

    private func makeBody() -> some View {
        // TODO: Logic here
        cases
    }
}

struct UseSwitchStatement {
    let animal: Animal = .cat

    var body: some View {
        VStack {
            Switch(animal) {
                Case(Animal.cat) {
                    Text("cat")
                }
                Case(Animal.dog) {
                    Text("dog")
                }
                Case(Animal.mouse) {
                    Text("mouse")
                }
            }
        }
    }
}

Use MakeView

Another solution is to use a MakeView view, this is more generic as it can execute any functions

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enum Animal: String {
    case cat
    case dog
    case mouse
}

struct MakeView: View {
    let make: () -> AnyView

    var body: some View {
        make()
    }
}

struct UseMakeView: View {
    let animal: Animal = .cat

    var body: some View {
        MakeView {
            switch self.animal {
            case .cat:
                return Text("cat").erase()
            case .dog:
                return Text("dog").erase()
            case .mouse:
                return Text("mouse").erase()
            }
        }
    }
}
a few seconds read (About 81 words)

How to test DispatchQueue in Swift

Issue #646

Sync the DispatchQueue

Pass DispatchQueue and call queue.sync to sync all async works before asserting

Use mock

Use DispatchQueueType and in mock, call the work immediately

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import Foundation

public protocol DispatchQueueType {
    func async(execute work: @escaping @convention(block) () -> Void)
}

extension DispatchQueue: DispatchQueueType {
    public func async(execute work: @escaping @convention(block) () -> Void) {
        async(group: nil, qos: .unspecified, flags: [], execute: work)
    }
}

final class MockDispatchQueue: DispatchQueueType {
    func async(execute work: @escaping @convention(block) () -> Void) {
        work()
    }
}
a few seconds read (About 54 words)

How to assert asynchronously in XCTest

Issue #644

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import XCTest

extension XCTestCase {
    /// Asynchronously assertion
    func XCTAssertWait(
        timeout: TimeInterval = 1,
        _ expression: @escaping () -> Void,
        _: String = "",
        file _: StaticString = #file,
        line _: UInt = #line
    ) {
        let expectation = self.expectation(description: #function)
        DispatchQueue.main.asyncAfter(deadline: .now() + timeout) {
            expression()
            expectation.fulfill()
        }

        let waiter = XCTWaiter()
        XCTAssertTrue(waiter.wait(for: [expectation], timeout: timeout + 1) == .completed)
    }
}
a few seconds read (About 101 words)

How to format percent in Swift

Issue #639

Never use String(format: "%.2f %%", 1.2 because each region can have different separator and placement of percent sign.

Use NumberFormatter instead

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let formatter = NumberFormatter()
formatter.numberStyle = .percent
formatter.minimumIntegerDigits = 1
formatter.maximumIntegerDigits = 3
formatter.maximumFractionDigits = 2
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formatter.locale = Locale(identifier: "en_US")
formatter.string(from: NSDecimalNumber(decimal: 1.2 / 100)) // 0.12%

formatter.locale = Locale(identifier: "nb_NO")
formatter.string(from: NSDecimalNumber(decimal: 1.2 / 100)) // 0,12 %

Note that the space created by NumberFormatter is a non breakable space \u{00a0}, which can be created by Alt Space. This non breakable space is useful in UILabel when you want the whole word to stick together

a few seconds read (About 96 words)

How to declare commands in Xcode extensions

Issue #638

Use commandDefinitions in XCSourceEditorExtension. 

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import Foundation
import XcodeKit

class SourceEditorExtension: NSObject, XCSourceEditorExtension {
    func extensionDidFinishLaunching() {

    }
    
    var commandDefinitions: [[XCSourceEditorCommandDefinitionKey: Any]] {
        func makeDef(
            _ className: String,
            _ commandName: String
        ) -> [XCSourceEditorCommandDefinitionKey: Any] {
            guard let bundleId = Bundle(for: type(of: self)).bundleIdentifier else { return [:] }

            return [
                XCSourceEditorCommandDefinitionKey.identifierKey: bundleId + className,
                XCSourceEditorCommandDefinitionKey.classNameKey: className,
                XCSourceEditorCommandDefinitionKey.nameKey: commandName
            ]
        }

        return [
            makeDef(TypeCommand.className(), "Type"),
            makeDef(ReloadCommand.className(), "Reload"),
        ]
    }
}

There is a weird crash that we can’t seem to declare functions or use commandDefinitions, the workaround is to declare in plist

Read more

a few seconds read (About 96 words)

How to declare commands in Xcode extenstions

Issue #638

Use commandDefinitions in XCSourceEditorExtension. 

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import Foundation
import XcodeKit

class SourceEditorExtension: NSObject, XCSourceEditorExtension {
    func extensionDidFinishLaunching() {

    }
    
    var commandDefinitions: [[XCSourceEditorCommandDefinitionKey: Any]] {
        func makeDef(
            _ className: String,
            _ commandName: String
        ) -> [XCSourceEditorCommandDefinitionKey: Any] {
            guard let bundleId = Bundle(for: type(of: self)).bundleIdentifier else { return [:] }

            return [
                XCSourceEditorCommandDefinitionKey.identifierKey: bundleId + className,
                XCSourceEditorCommandDefinitionKey.classNameKey: className,
                XCSourceEditorCommandDefinitionKey.nameKey: commandName
            ]
        }

        return [
            makeDef(TypeCommand.className(), "Type"),
            makeDef(ReloadCommand.className(), "Reload"),
        ]
    }
}

There is a weird crash that we can’t seem to declare functions or use commandDefinitions, the workaround is to declare in plist

Read more

a minute read (About 201 words)

How to disable ring type in TextField in SwiftUI

Issue #636

Normally we can just wrap NSTextField

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struct SearchTextField: NSViewRepresentable {
    @Binding var text: String
    var hint: String
    var onCommit: (String) -> Void

    func makeNSView(context: NSViewRepresentableContext<SearchTextField>) -> NSTextField {
        let tf = NSTextField()
        tf.focusRingType = .none
        tf.isBordered = false
        tf.isEditable = true
        tf.isSelectable = true
        tf.drawsBackground = false
        tf.delegate = context.coordinator
        tf.font = NSFont(name: OpenSans.bold.rawValue, size: 14)
        tf.placeholderString = hint
        return tf
    }

    func updateNSView(
        _ nsView: NSTextField,
        context: NSViewRepresentableContext<SearchTextField>
    ) {
        nsView.font = NSFont(name: OpenSans.bold.rawValue, size: 14)
        nsView.stringValue = text
    }

    func makeCoordinator() -> SearchTextField.Coordinator {
        Coordinator(parent: self)
    }

    class Coordinator: NSObject, NSTextFieldDelegate  {
        let parent: SearchTextField
        init(parent: SearchTextField) {
            self.parent = parent
        }

        func controlTextDidChange(_ obj: Notification) {
            let textField = obj.object as! NSTextField
            parent.text = textField.stringValue
        }

        func control(_ control: NSControl, textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
            if (commandSelector == #selector(NSResponder.insertNewline(_:))) {
                self.parent.onCommit(textView.string)
                return true
            } else {
                return false
            }
        }
    }
}

But there is a weird Appstore rejection where the textfield is not focusable. The workaround is to use TextField

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extension NSTextField {
    open override var focusRingType: NSFocusRingType {
        get { .none }
        set { }
    }
}

TextField(
    "What's next?",
    text: $text,
    onCommit: { self.onAdd(self.text) }
)
.font(.system(size: 14, weight: .semibold, design: .rounded))
.textFieldStyle(PlainTextFieldStyle())
.padding(1)
.background(RoundedRectangle(cornerRadius: 2).stroke(Color.white))
a few seconds read (About 100 words)

How to handle enter key in NSTextField

Issue #635

1
textField.delegate = self
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NSTextFieldDelegate

func control(_ control: NSControl, textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
    if (commandSelector == #selector(NSResponder.insertNewline(_:))) {
        // Do something against ENTER key
        print("enter")
        return true
    } else if (commandSelector == #selector(NSResponder.deleteForward(_:))) {
        // Do something against DELETE key
        return true
    } else if (commandSelector == #selector(NSResponder.deleteBackward(_:))) {
        // Do something against BACKSPACE key
        return true
    } else if (commandSelector == #selector(NSResponder.insertTab(_:))) {
        // Do something against TAB key
        return true
    } else if (commandSelector == #selector(NSResponder.cancelOperation(_:))) {
        // Do something against ESCAPE key
        return true
    }

    // return true if the action was handled; otherwise false
    return false
}
a few seconds read (About 41 words)

How to decode with default case for enum in Swift

Issue #634

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public enum Weapon: String, Decodable {
    case sword = "SWORD"
    case gun = "GUN"
    case unknown = "UNKNOWN"

    public init(from decoder: Decoder) throws {
        let rawValue = try decoder.singleValueContainer().decode(String.self)
        self = Weapon(rawValue: rawValue) ?? .unknown
    }
}
a few seconds read (About 58 words)

How to conditionally apply modifier in SwiftUI

Issue #633

Use autoclosure and AnyView

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@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
public extension View {
    func applyIf<T: View>(_ condition: @autoclosure () -> Bool, apply: (Self) -> T) -> AnyView {
        if condition() {
            return apply(self).erase()
        } else {
            return self.erase()
        }
    }
}
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Button(action: onSearch) {
    Image("search")
        .resizable()
        .styleButton()
        .overlay(ToolTip("Search"))
}
.buttonStyle(BorderlessButtonStyle())
.applyIf(showsSearch, apply: {
    $0.foregroundColor(Color.orange)
})
a few seconds read (About 37 words)

How to toggle with animation in SwiftUI

Issue #632

Use Group

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private func makeHeader() -> some View {
    Group {
        if showsSearch {
            SearchView(
                onSearch: onSearch
            )
            .transition(.move(edge: .leading))
        } else {
            InputView(
                onAdd: onAdd
            )
            .transition(.move(edge: .leading))
        }
    }
}

withAnimation {
    self.showsSearch.toggle()
}
a few seconds read (About 92 words)

How to show context popover from SwiftUI for macOS

Issue #630

For SwiftUI app using NSPopover, to show context popover menu, we can ask for windows array, get the _NSPopoverWindow and calculate the position. Note that origin of macOS screen is bottom left

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(lldb) po NSApp.windows
▿ 2 elements
  - 0 : <NSStatusBarWindow: 0x101a02700>
  - 1 : <_NSPopoverWindow: 0x101c01060>
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let handler = MenuHandler()
handler.add(title: "About", action: onAbout)
handler.add(title: "Quit", action: onQuit)

guard let window = NSApp.windows.last else { return }
let position = CGPoint(
    x: window.frame.maxX - 100,
    y: window.frame.minY + 80
)
handler.menu.popUp(positioning: nil, at: position, in: nil)
a few seconds read (About 109 words)

How to make segmented control in SwiftUI for macOS

Issue #629

Use Picker with SegmentedPickerStyle.

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Picker(selection: $preferenceManager.preference.display, label: EmptyView()) {
    Image("grid")
        .resizable()
    .padding()
        .tag(0)
    Image("list")
        .resizable()
        .tag(1)
}.pickerStyle(SegmentedPickerStyle())
.frame(width: 50)
.padding(.leading, 16)
.padding(.trailing, 24)

Alternatively, we can make custom NSSegmentedControl

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import AppKit
import SwiftUI

struct MySegmentControl: NSViewRepresentable {
    func makeCoordinator() -> MySegmentControl.Coordinator {
        Coordinator(parent: self)
    }

    func makeNSView(context: NSViewRepresentableContext<MySegmentControl>) -> NSSegmentedControl {
        let control = NSSegmentedControl(
            images: [
                NSImage(named: NSImage.Name("grid"))!,
                NSImage(named: NSImage.Name("list"))!
            ],
            trackingMode: .selectOne,
            target: context.coordinator,
            action: #selector(Coordinator.onChange(_:))
        )
        return control
    }

    func updateNSView(_ nsView: NSSegmentedControl, context: NSViewRepresentableContext<MySegmentControl>) {

    }

    class Coordinator {
        let parent: MySegmentControl
        init(parent: MySegmentControl) {
            self.parent = parent
        }

        @objc
        func onChange(_ control: NSSegmentedControl) {

        }
    }
}
a few seconds read (About 70 words)

How to iterate over XCUIElementQuery in UITests

Issue #628

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extension XCUIElementQuery: Sequence {
    public typealias Iterator = AnyIterator<XCUIElement>
    public func makeIterator() -> Iterator {
        var index = UInt(0)
        return AnyIterator {
            guard index < self.count else { return nil }

            let element = self.element(boundBy: Int(index))
            index = index + 1
            return element
        }
    }
}

extension NSPredicate {
    static func label(contains string: String) -> NSPredicate {
        NSPredicate(format: "label CONTAINS %@", string)
    }
}

let books = app.collectionViews.cells.matching(
    NSPredicate.label(contains: "book")
)

for book in books {

}
a few seconds read (About 78 words)

How to check if NSColor is light

Issue #627

Algorithm from https://www.w3.org/WAI/ER/WD-AERT/#color-contrast

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extension NSColor {
    var isLight: Bool {
        guard
            let components = cgColor.components,
            components.count >= 3
        else { return false }

        let brightness = ((components[0] * 299) + (components[1] * 587) + (components[2] * 114)) / 1000
        return brightness > 0.5
    }
}

Then we can apply contrast color for our Text

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extension Text {
    func applyColorBaseOnBackground(_ color: NSColor?) -> some View {
        guard let color = color else { return self }
        if color.isMyLight {
            return self.foregroundColor(Color.black)
        } else {
            return self
        }
    }
}
a few seconds read (About 104 words)

How to trigger onAppear in SwiftUI for macOS

Issue #626

SwiftUI does not trigger onAppear and onDisappear like we expect. We can use NSView to trigger

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import SwiftUI

struct AppearAware: NSViewRepresentable {
    var onAppear: () -> Void

    func makeNSView(context: NSViewRepresentableContext<AppearAware>) -> AwareView {
        let view = AwareView()
        view.onAppear = onAppear
        return view
    }

    func updateNSView(_ nsView: AwareView, context: NSViewRepresentableContext<AppearAware>) {

    }
}

final class AwareView: NSView {
    private var trigged: Bool = false
    var onAppear: () -> Void = {}

    override func viewDidMoveToSuperview() {
        super.viewDidMoveToSuperview()

        guard !trigged else { return }
        trigged = true
        onAppear()
    }
}

Then we can use it as an hidden view, like in a ZStack

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ZStack {
    AppearAware(onAppear: {
        LocalImageCache.shared.load(url: url) { image in
            self.image = image
        }
    })
    Image(image)
}
a few seconds read (About 56 words)

How to force refresh in ForEach in SwiftUI for macOS

Issue #625

For some strange reasons, content inside ForEach does not update with changes in Core Data NSManagedObject. The workaround is to introduce salt, like UUID just to make state change

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struct NoteRow: View {
    let note: Note
    let id: UUID
}

List {
    ForEach(notes) { note in
        NoteRow(note: note, id: UUID())
    }
}
2 minutes read (About 342 words)

How to access bookmark url in macOS

Issue #624

By default the approaches above grant you access while the app remains open. When you quit the app, any folder access you had is lost.

To gain persistent access to a folder even on subsequent launches, we’ll have to take advantage of a system called Security-Scoped Bookmarks.

Add entitlements

Use of app-scoped bookmarks and URLs

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<key>com.apple.security.files.user-selected.read-only</key>
<true/>
<key>com.apple.security.files.bookmarks.app-scope</key>
<true/>

Enabling Security-Scoped Bookmark and URL Access

If you want to provide your sandboxed app with persistent access to file system resources, you must enable security-scoped bookmark and URL access. Security-scoped bookmarks are available starting in macOS v10.7.3.

To add the bookmarks.app-scope or bookmarks.document-scope entitlement, edit the target’s .entitlements property list file using the Xcode property list editor. Use the entitlement keys shown in Table 4-4, depending on which type of access you want. Use a value of for each entitlement you want to enable. You can enable either or both entitlements.

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func saveBookmark(item: ShortcutItem) {
    guard let url = item.fileUrl else { return  }
    do {
        let bookmarkData = try url.bookmarkData(
            options: .withSecurityScope,
            includingResourceValuesForKeys: nil,
            relativeTo: nil
        )

        item.bookmark = bookmarkData
    } catch {
        print("Failed to save bookmark data for \(url)", error)
    }
}

func loadBookmark(item: ShortcutItem) -> URL? {
    guard let data = item.bookmark else { return nil }
    do {
        var isStale = false
        let url = try URL(
            resolvingBookmarkData: data,
            options: .withSecurityScope,
            relativeTo: nil,
            bookmarkDataIsStale: &isStale
        )
        if isStale {
            saveBookmark(item: item)
        }
        return url
    } catch {
        print("Error resolving bookmark:", error)
        return nil
    }
}


_ = url.startAccessingSecurityScopedResource()
NSWorkspace.shared.open(url)
url.stopAccessingSecurityScopedResource()
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_ = url.startAccessingSecurityScopedResource()
NSWorkspace.shared.selectFile(
    url.path,
    inFileViewerRootedAtPath: url.deletingLastPathComponent().path
)
url.stopAccessingSecurityScopedResource()

Read more

a minute read (About 205 words)

How to batch delete in Core Data

Issue #622

Read Implementing Batch Deletes

If the entities that are being deleted are not loaded into memory, there is no need to update your application after the NSBatchDeleteRequest has been executed. However, if you are deleting objects in the persistence layer and those entities are also in memory, it is important that you notify the application that the objects in memory are stale and need to be refreshed.

To do this, first make sure the resultType of the NSBatchDeleteRequest is set to NSBatchDeleteRequestResultType.resultTypeObjectIDs before the request is executed. When the request has completed successfully, the resulting NSPersistentStoreResult instance that is returned will have an array of NSManagedObjectID instances referenced in the result property. That array of NSManagedObjectID instances can then be used to update one or more NSManagedObjectContext instances.

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let fetchRequest: NSFetchRequest<NSFetchRequestResult> = Book.fetchRequest()
let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
deleteRequest.resultType = .resultTypeObjectIDs

do {
    let context = CoreDataManager.shared.container.viewContext
    let result = try context.execute(
        deleteRequest
    )

    guard
        let deleteResult = result as? NSBatchDeleteResult,
        let ids = deleteResult.result as? [NSManagedObjectID]
    else { return }

    let changes = [NSDeletedObjectsKey: ids]
    NSManagedObjectContext.mergeChanges(
        fromRemoteContextSave: changes,
        into: [context]
    )
} catch {
    print(error as Any)
}
a minute read (About 126 words)

How to make TextField focus in SwiftUI for macOS

Issue #620

For NSWindow having levelother than .normal, need to override key and main property to allow TextField to be focusable

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class FocusWindow: NSWindow {
    override var canBecomeKey: Bool  { true }
    override var canBecomeMain: Bool { true }
}

Furthermore to customize TextField, consider using custom

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import SwiftUI
import AppKit

struct MyTextField: NSViewRepresentable {
    @Binding var text: String

    func makeNSView(context: NSViewRepresentableContext<MyTextField>) -> NSTextField {
        let tf = NSTextField()
        tf.focusRingType = .none
        tf.isBordered = false
        tf.drawsBackground = false
        tf.delegate = context.coordinator
        return tf
    }

    func updateNSView(_ nsView: NSTextField, context: NSViewRepresentableContext<MyTextField>) {
        nsView.stringValue = text
    }

    func makeCoordinator() -> MyTextField.Coordinator {
        Coordinator(parent: self)
    }

    class Coordinator: NSObject, NSTextFieldDelegate  {
        let parent: MyTextField
        init(parent: MyTextField) {
            self.parent = parent
        }

        func controlTextDidChange(_ obj: Notification) {
            let textField = obj.object as! NSTextField
            parent.text = textField.stringValue
        }
    }
}
a few seconds read (About 48 words)

How to show popover for item in ForEach in SwiftUI

Issue #618

Create custom Binding

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List {
    ForEach(self.items) { (item: item) in
        ItemRowView(item: item)
            .popover(isPresented: self.makeIsPresented(item: item)) {
                ItemDetailView(item: item)
            }
    }
}

func makeIsPresented(item: Item) -> Binding<Bool> {
    return .init(get: {
        return self.selectedId == item.id
    }, set: { _ in
        self.selectedId = nil
    })
}
a few seconds read (About 99 words)

How to make tooltip in SwiftUI for macOS

Issue #617

Create empty NSView and use as overlay. Need to updateNSView in case we toggle the state of tooltip

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import SwiftUI

struct Tooltip: NSViewRepresentable {
    let tooltip: String

    func makeNSView(context: NSViewRepresentableContext<Tooltip>) -> NSView {
        let view = NSView()
        view.toolTip = tooltip
        return view
    }

    func updateNSView(_ nsView: NSView, context: NSViewRepresentableContext<Tooltip>) {
        nsView.toolTip = tooltip
    }
}
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Button(action: self.onGear) {
    Image("gear")
        .styleButton()
}
.overlay(Tooltip(tooltip: "Settings"))
.buttonStyle(BorderlessButtonStyle())

Sometimes it’s better to add overlay tooltip to Image inside Button to avoid blocking

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Button(action: self.onGear) {
    Image("gear")
        .styleButton()
       .overlay(Tooltip(tooltip: "Settings"))
}
.buttonStyle(BorderlessButtonStyle())
a minute read (About 122 words)

How to make tab view in SwiftUI

Issue #614

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struct MyTabView: View {
    @EnvironmentObject
    var preferenceManager: PreferenceManager

    var body: some View {
        VOrH(isVertical: preferenceManager.preference.position.isVertical) {
            OneTabView(image: "one", text: "One", tab: .one)
            OneTabView(image: "two", text: "Two", tab: .two)
            OneTabView(image: "three", text: "Three", tab: .three)
            Spacer()
        }
    }
}

struct OneTabView: View {
    @EnvironmentObject
    var preferenceManager: PreferenceManager

    let image: String
    let text: String
    let tab: Tab

    var selected: Bool {
        preferenceManager.preference.tab == tab
    }

    var body: some View {
        Button(action: { self.preferenceManager.preference.tab = self.tab }) {
            VStack(spacing: 2) {
                Image(image)
                    .renderingMode(selected ? .original : .template)
                    .resizable()
                    .aspectRatio(contentMode: .fit)
                    .frame(height: 20)
                Text(text)
                    .font(.system(.caption, design: .rounded))
                    .fontWeight(selected ? .semibold : .none)
            }
        }
        .padding(.horizontal, 4)
        .buttonStyle(BorderlessButtonStyle())
        .frame(width: 60, height: 50)
        .background(selected ? R.color.selectedTabBackground : Color.clear)
        .cornerRadius(4)
    }
}
a minute read (About 196 words)

How to present NSWindow modally

Issue #612

Use runModal

This method runs a modal event loop for the specified window synchronously. It displays the specified window, makes it key, starts the run loop, and processes events for that window. (You do not need to show the window yourself.) While the app is in that loop, it does not respond to any other events (including mouse, keyboard, or window-close events) unless they are associated with the window. It also does not perform any tasks (such as firing timers) that are not associated with the modal run loop. In other words, this method consumes only enough CPU time to process events and dispatch them to the action methods associated with the modal window.

Specify level in windowDidBecomeKey

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let controller = SettingsWindowController()
NSApp.runModal(for: controller.window!)

final class SettingsWindowController: NSWindowController, NSWindowDelegate {
    init() {
        let mainView = SettingsView()

        let window = NSWindow(
            contentRect: CGRect(x: 0, y: 0, width: 500, height: 300),
            styleMask: [.titled, .closable],
            backing: .buffered,
            defer: false
        )
        let hosting = NSHostingView(rootView: mainView)
        window.contentView = hosting

        super.init(window: window)
        window.delegate = self
    }
    
    func windowDidBecomeKey(_ notification: Notification) {
        window?.level = .statusBar
    }
    func windowWillClose(_ notification: Notification) {
        NSApp.stopModal()
    }
}
a few seconds read (About 34 words)

How to use Picker with enum in SwiftUI

Issue #611

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enum WindowPosition: String, CaseIterable {
    case left
    case top
    case bottom
    case right
}
Picker(selection: $preference.position, label: Text("Position")) {
    ForEach(WindowPosition.allCases, id: \.self) {
        Text($0.rawValue)
    }
}
a few seconds read (About 98 words)

How to use visual effect view in NSWindow

Issue #610

Set NSVisualEffectView as contentView of NSWindow, and our main view as subview of it. Remember to set frame or autoresizing mask as non-direct content view does not get full size as the window

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let mainView = MainView()
    .environment(\.managedObjectContext, coreDataManager.container.viewContext)

window = NSWindow(
    contentRect: .zero,
    styleMask: [.fullSizeContentView],
    backing: .buffered,
    defer: false
)
window.titlebarAppearsTransparent = true
window.center()
window.level = .statusBar
window.setFrameAutosaveName("MyApp")

let visualEffect = NSVisualEffectView()
visualEffect.blendingMode = .behindWindow
visualEffect.state = .active
visualEffect.material = .appearanceBased

let hosting = NSHostingView(rootView: mainView)
window.contentView = visualEffect
visualEffect.addSubview(hosting)
hosting.autoresizingMask = [.width, .height]
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