Issue #905 Protect mutable state with Swift actors Actor reentrancy Imagine we have two different concurrent tasks trying to fetch the same image at the same time. The first sees that there is no cache entry, proceeds to start downloading the image from the server, and then gets suspended because the download will take a while. While the first task is downloading the image, a new image might be deployed to the server under the same URL....
Issue #904 Consider this code where we have an ObservableObject with fetch1 and async fetch2, and a fetch inside ContentView Here the observation in Xcode 14 ViewModel.fetch1: run on main thread ViewModel.fetch2: run on cooperative thread pool ContentView.fetch: run on main thread import SwiftUI import CoreData import Combine class ViewModel: ObservableObject { @Published var string = "" func fetch1() { let url = URL(string: "https://google.com")! let data = try! Data(contentsOf: url) self....
Issue #903 let image = NSImage(contentsOf: url) let imageView = NSImageView(image: image) image.animates = true
Issue #900 Listen to didActivateApplicationNotification and check that it is not our app NSWorkspace.shared.notificationCenter .publisher(for: NSWorkspace.didActivateApplicationNotification) .sink(receiveValue: { [weak self] note in guard let app = note.userInfo?[NSWorkspace.applicationUserInfoKey] as? NSRunningApplication, app.bundleIdentifier != Bundle.main.bundleIdentifier else { return } self?.frontMostApp = app }) .store(in: &bag)
Issue #899 Use NSTitlebarAccessoryViewController var titleBarAccessoryVC: NSTitlebarAccessoryViewController { let vc = NSTitlebarAccessoryViewController() let view = HStack { Spacer() Button { } label: { Text("Save") } .buttonStyle(.borderedProminent) .controlSize(.large) } .padding(.horizontal) vc.view = NSHostingView(rootView: view) return vc } let window: NSWindow = ... window.addTitlebarAccessoryViewController(titleBarAccessoryVC)
Issue #898 Change element position using either offset or position, and use DragGesture Use GestureState to store the updating startDragLocation to keep the start location when drag begins, so we can add translation struct MoveModifier: ViewModifier { @Binding var position: CGPoint @GestureState private var startLocation: CGPoint? func body(content: Content) -> some View { content .gesture(gesture) } private var gesture: some Gesture { DragGesture() .onChanged { value in var position = startLocation ?...
Issue #896 Use underscore _focus we get access to underlying FocusState object, but underscore _ is private to a View hence can’t be used in extension If we want to pass FocusState to another View or in extension, we can pass its Binding enum FocusElement: Hashable { case name case email } struct ParentView: View { @FocusState var focus: FocusElement? var body: some View { ChildView1(focus: _focus) ChildView2(focus: $focus) } } struct ChildView1: View { @FocusState var focus: FocusElement?...
Issue #895 Apply .move on reversed array List(selection: $viewModel.selectedBook) { ForEach(viewModel.books.reversed()) { book in BookCell(book: book) } .onMove { source, dest in var reversed = Array(viewModel.books.reversed()) reversed.move(fromOffsets: source, toOffset: dest) viewModel.books = reversed.reversed() } }
Issue #891 Below are my favorite WWDC videos. My focus is to use SwiftUI to make useful apps with great UX. I don’t pay much attention to new frameworks as they come and go, but the underlying reasons and design principles are worth remembering. WWDC23 The SwiftUI cookbook for focus Discussing some of the things that you can do with focus APIs in SwiftUI to cook up a really great user experience...
Issue #890 In WWDC21, WWDC22 Apple provide a Slack channel https://wwdc22.slack.com/ for people to interact with Apple engineers in digital lounges. Here I note down some interesting Q&As WWDC22 What’s the difference between a custom ViewModifier vs View extension Q: What’s the difference between a custom ViewModifier (without DynamicProperty) that uses some built-in modifiers in body(content:), and a custom View extension func that just use those built-in modifiers? Similarly, what’s the difference between a custom ViewModifier with some DynamicProperty and a custom View with some DynamicProperty (also has a @ViewBuilder content property to receive content to modify) ?...
Issue #890 Interesting SwiftUI Q&A during WWDC22 What’s the difference between a custom ViewModifier vs View extension Q: What’s the difference between a custom ViewModifier (without DynamicProperty) that uses some built-in modifiers in body(content:), and a custom View extension func that just use those built-in modifiers? Similarly, what’s the difference between a custom ViewModifier with some DynamicProperty and a custom View with some DynamicProperty (also has a @ViewBuilder content property to receive content to modify) ?...
Issue #889 What’s new in SwiftUI New EnvironmentValues TextField inside Alert List uses UICollectionView See gist https://gist.github.com/onmyway133/fc08111964984ef544a176a6e9806c18 ButtonStyle composition Section("Hashtags") { VStack(alignment: .leading) { HStack { Toggle("#Swiftastic", isOn: $swiftastic) Toggle("#WWParty", isOn: $wwdcParty) } HStack { Toggle("#OffTheCharts", isOn: $offTheCharts) Toggle("#OneMoreThing", isOn: $oneMoreThing) } } .toggleStyle(.button) .buttonStyle(.bordered) } Customize Charts struct MonthlySalesChart: View { var body: some View { Chart(data, id: \.month) { BarMark( x: .value("Month", $0.month, unit: .month), y: .value("Sales", $0.sales) ) } ....
Issue #888 Embrace Swift generics This generic pattern is really common, so there’s a simpler way to express it. Instead of writing a type parameter explicitly, we can express this abstract type in terms of the protocol conformance by writing “some Animal”. The “some” in “some Animal” indicates that there is a specific type that you’re working with. func feed<A>(animal: A) where A: Animal {} func feed(animal: some Animal) An abstract type that represents a placeholder for a specific concrete type is called an opaque type....
Issue #887 What’s new https://www.whatsnewinswift.com https://www.hackingwithswift.com/articles/249/whats-new-in-swift-5-7 https://www.hackingwithswift.com/articles/247/whats-new-in-swift-5-6
Issue #886 SwiftUI iOS 16 https://bigmountainstudio.github.io/What-is-new-in-SwiftUI/ https://swiftwithmajid.com/2022/06/07/what-is-new-in-swiftui-after-wwdc22/ https://www.hackingwithswift.com/articles/250/whats-new-in-swiftui-for-ios-16 SwiftUI https://www.hackingwithswift.com/articles/235/whats-new-in-swiftui-for-ios-15 https://www.hackingwithswift.com/articles/221/whats-new-in-swiftui-for-ios-14 https://talk.objc.io/collections/swiftui-layout-explained SwiftUI practices 8 Common SwiftUI Mistakes – and how to fix them! https://www.youtube.com/watch?v=qkcKTJhDyLs 5 Steps to Better SwiftUI Views https://www.youtube.com/watch?v=uC3X4FoielU SwiftUI tips and tricks https://www.hackingwithswift.com/quick-start/swiftui/swiftui-tips-and-tricks SwiftUI Tips https://www.youtube.com/watch?v=M2e1Z9enFHo Tips thread https://twitter.com/twostraws/status/1465801488920465414?s=20 Quick Friday tips https://twitter.com/search?src=typed_query&q=%22Quick%20Friday%20tip%22%20(from%3Ascottsmithdev Reference https://github.com/onmyway133/awesome-swiftui https://swiftontap.com/
Issue #885 Create NSBitmapImageRep with preferred size and draw NSImage onto that. Need to construct NSBitmapImageRep specifically instead of using convenient initializers like NSBitmapImageRep(data:), NSBitmapImageRep(cgImage:) to avoid device dependant resolution issue. extension NSImage { func pngData( size: CGSize, imageInterpolation: NSImageInterpolation = .high ) -> Data? { guard let bitmap = NSBitmapImageRep( bitmapDataPlanes: nil, pixelsWide: Int(size.width), pixelsHigh: Int(size.height), bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: .deviceRGB, bitmapFormat: [], bytesPerRow: 0, bitsPerPixel: 0 ) else { return nil } bitmap....
Issue #883 Read more https://www.objc.io/blog/2020/11/10/hstacks-child-ordering/ https://talk.objc.io/collections/swiftui-layout-explained https://rensbr.eu/blog/swiftui-escaping-closures/ https://rensbr.eu/blog/swiftui-render-loop/ https://movingparts.io/variadic-views-in-swiftui
Issue #882 In SwiftUI, .popover shows as popover on Mac and iPad, but as .sheet on iPhone (compact size class) We can use minWidth, minHeight to specify sizes on Mac and iPad. On iPhone, we can check and wrap it inside NavigationView. Setting navigationTitle without being embedded in NavigationView has not effect `` .popover(isPresented: $showsEdit) { EditSnippetView( snippet: snippet ) .frame(minWidth: 300, alignment: .topLeading) .navigationTitle("Tags") .modifier( EmbedInNavigationModifier() ) }
Issue #881 Specify optional value for List(selection:). This keeps selection on macOS, but not on iPad. On iPad each row in the List needs to be NavigationLink, no need for .tag. The selection is not updated, need to manually update with onTapGesture For List selection to work, make sure selection binding type matches. Preferablly using ID than Self Need to specify id in ForEach for List to infer tag. Otherwise, need to specify tag for cell struct Sidebaer: View { class ViewModel: ObservableObject { @Published var group: BookGroup?...
Issue #878 Note that Explicit id is needed, although Book already conforms to Identifiable selection needs a default value class BookViewModel: ObservableObject { @Published var books: [Book] = [] @Published var selectedBooks: Set<Book> = [] } List(selection: $viewModel.selectedBooks) { ForEach(viewModel.books, id: \.self) { book in BookRow(book: book) } }