How to use Core Data

Issue #785 Some links to learn Core Data Responding to changes in a managed object context Calling mergeChanges on a managed object context will automatically refresh any managed objects that have changed. This ensures that your context always contains all the latest information. Note that you don’t have to call mergeChanges on a viewContext when you set its automaticallyMergesChangesFromParent property to true. In that case, Core Data will handle the merge on your behalf....

February 26, 2021 · 5 min · Khoa Pham

How to force resolve Swift Package in Xcode

Issue #784 Every time I switch git branches, SPM packages seem to be invalidated and Xcode does not fetch again, no matter how many times I reopen. Running xcodebuild -resolvePackageDependencies does fetch but Xcode does not recognize the resolved packages and still reports missing packages. The good thing is under menu File -> Swift Packages there are options to reset and resolve packages...

February 26, 2021 · 1 min · Khoa Pham

How to listen to Published outside of SwiftUI view

Issue #782 Use $ to access Publisher final class Store: ObservableObject { @Published var showsSideWindow: Bool = false } var anyCancellables = Set<AnyCancellable>() store.$showsSideWindow .removeDuplicates() .throttle(for: 0.2, scheduler: RunLoop.main, latest: true) .receive(on: RunLoop.main) .sink(receiveValue: { shows in preferenceManager.reloadPosition(shows: shows) }) .store(in: &anyCancellables) Updated at 2021-02-25 21:56:42...

February 25, 2021 · 1 min · Khoa Pham

How to build container view in SwiftUI

Issue #780 To make a container view that accepts child content, we use ViewBuilder struct ContainerView<Content: View>: View { let content: Content init(@ViewBuilder content: () -> Content) { self.content = content() } var body: some View { content } } From Swift 5.4, it can synthesize the init, so we can declare resultBuilder for stored property struct AwesomeContainerView<Content: View>: View { @ViewBuilder let content: Content var body: some View { content } } Updated at 2021-02-24 21:22:49...

February 24, 2021 · 1 min · Khoa Pham

How to tune performance with ButtonBehavior in SwiftUI

Issue #779 With Xcode 12.4, macOS 11.0 app. Every time we switch the system dark and light mode, the CPU goes up to 100%. Instruments show that there’s an increasing number of ButtonBehavior Suspect State in a row in LazyVStack Every cell has its own toggle state struct Cell: View { enum ToggleState { case general case request case response } let item: Item @State private var toggleState: ToggleState = ....

February 24, 2021 · 1 min · Khoa Pham

How to make simple search bar in SwiftUI

Issue #776 We need to use a custom Binding to trigger onChange as onEditingChanged is only called when the user selects the textField, and onCommit is only called when return or done button on keyboard is tapped. import UIKit import SwiftUI import EasySwiftUI struct SearchBar: View { @Binding var searchText: String let onChange: () -> Void @State private var showsCancelButton: Bool = false var body: some View { return HStack { textField cancelButton } } private var searchTextBinding: Binding<String> { Binding<String>(get: { searchText }, set: { newValue in DispatchQueue....

February 17, 2021 · 1 min · Khoa Pham

How to add home screen quick action in SwiftUI

Issue #774 Start by defining your quick actions. You can use UIApplicationShortcutIcon(type:) for predefined icons, or use UIApplicationShortcutIcon(systemImageName:) for SFSymbol enum QuickAction: String { case readPasteboard case clear var shortcutItem: UIApplicationShortcutItem { switch self { case .readPasteboard: return UIApplicationShortcutItem( type: rawValue, localizedTitle: "Read Pasteboard", localizedSubtitle: "", icon: UIApplicationShortcutIcon(type: .add), userInfo: nil ) case .clear: return UIApplicationShortcutItem( type: rawValue, localizedTitle: "Clear Pasteboard", localizedSubtitle: "", icon: UIApplicationShortcutIcon(systemImageName: SFSymbol.wind.rawValue), userInfo: nil ) } } } Add a service to store selected quick action....

February 10, 2021 · 2 min · Khoa Pham

How to use EquatableView in SwiftUI

Issue #773 From John Harper ’s tweet SwiftUI assumes any Equatable.== is a true equality check, so for POD views it compares each field directly instead (via reflection). For non-POD views it prefers the view’s == but falls back to its own field compare if no ==. EqView is a way to force the use of ==. When it does the per-field comparison the same rules are applied recursively to each field (to choose direct comparison or == if defined)....

February 8, 2021 · 1 min · Khoa Pham

How to add new property in Codable struct in SwiftUI

Issue #772 I use Codable structs in my apps for preferences, and bind them to SwiftUI views. If we add new properties to existing Codable, it can’t decode with old saved json as we require new properties. We can either do cutom decoding with container, but this can result in lots more code and mistakes if we have many properties inside our struct. The quick workaround is to declare new properties as optional, and use a computed property to wrap that....

February 8, 2021 · 1 min · Khoa Pham

How to handle escape in NSTextField in SwiftUI

Issue #770 Handle cancelOperation somewhere up in responder chain class MyWindow: NSWindow { let keyHandler = KeyHandler() override func cancelOperation(_ sender: Any?) { super.cancelOperation(sender) keyHandler.onEvent(.esc) } } ...

February 6, 2021 · 1 min · Khoa Pham