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Flush Metal rendering when program is paused in LLDB?
I watched a WWDC talk on LLDB, and they showed a nice trick of calling CATransaction.flush() from the debugger, to push changes to a UIView to the screen, even when the program was paused. Is there is a similar thing we can do with Metal? I'm using MTKView, but I can change to a lower level if that's required. The MTKView is paused, so I'm using setNeedsDisplay. As usual, I implement the draw delegate method to encode and commit a command buffer. If I do this from LLDB: metalView.setNeedsDisplay() CATransaction.flush() I can see that causes my draw function to run, but nothing shows up on screen. Is there something else we can do to flush those metal commands to the GPU and see them on screen while stepping through the program with the debugger?
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784
Nov ’21
SwiftUI Text inside Text interpolation bug?
Why the does this display "Hello1" and not "HelloWorld"? Then if I put a space between them it works as expected. (macOS 12.0.1) struct ContentView: View {     var body: some View {         let t1 = Text("Hello").foregroundColor(.red)         let t2 = Text("World").foregroundColor(.blue)         Text("\(t1)\(t2)")             .padding()             .frame(width: 200)     } }
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677
Nov ’21
TextField is mutating its model when not editing?
This minimal code demonstrates a problem I'm having. As you adjust the Slider (high precision numbers), the TextField sets the model, changing the number's precision to its format. But I only want it to use the 3-digit fraction for display, or if the user edits in the field. It shouldn't be mutating the model just because it's displaying the value, no? Is it a bug? It doesn't seem right to me. struct ContentView: View {     @State var number: Double = 0 // wrap binding to log the `set` calls     var textFieldBinding: Binding<Double> {         Binding { number } set: {             print("Setting from TextField: \($0)")             number = $0         }     }     var sliderBinding: Binding<Double> {         Binding { number } set: {             print("Setting from Slider: \($0)")             number = $0         }     }     var body: some View {         VStack {             TextField("Number", value: textFieldBinding, format: .number.precision(.fractionLength(3)))             Slider(value: sliderBinding, in: 0...5.0)         }.frame(maxWidth: 300)     } } When you drag the slider, you see stuff like: Setting from Slider: 1.0073260217905045 Setting from TextField: 1.007 ...
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337
Oct ’21
MagnificationGesture needs location?
I tried to replace UIKit's UIPinchGestureRecognizer with SwiftUI's MagnificationGesture, but it doesn't seem possible in my case. I use the location(in: UIView) function from the former, which allows me to zoom in on that point, specifically. It's a better experience when zooming in on an image. Can I get that info from the MaginificationGesture? In the example code I see only the CGFloat for the amount of magnification.
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430
Oct ’21
UIDocument no longer saving, error in URLByAppendingPathExtension
I've been working on an iOS app with UIDocuments. They were saving fine. Now all of a sudden, after unrelated changes, nothing will save. Here is the error printed in Xcode console: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL URLByAppendingPathExtension:]: component, components, or pathExtension cannot be nil.' log.debug("save to:\(self.document.fileURL)") document.save(to: document.fileURL, for: .forOverwriting) { success in ... } The log message there prints a valid URL.
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1k
Oct ’21
SwiftUI sheet size control on iPad
I want to show a custom confirmation dialog on my iPad. It pops up looking utterly ridiculous because the size is way bigger than it needs - inches of padding on all sides. Is there still no way to control a sheet size on iPad? Example code: struct ContentView: View {     @State var showSheet = false     var body: some View {         Button("Show sheet") {             showSheet = true         }.sheet(isPresented: $showSheet) {             VStack(spacing: 0) {                 Text("Title")                 Divider()                 Text("Line 1")                 Text("Line 2. Blah blah blah blah.")                 Divider()                 HStack {                     Button("Cancel") { showSheet = false }                     Divider()                     Button("OK") { showSheet = false }                 }.fixedSize(horizontal: false, vertical: true)             }             .frame(minWidth: 0, minHeight: 0)             .fixedSize()         }     } } The result:
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494
Sep ’21
Are Button actions on the MainActor?
I think they are, but I got myself into a situation with this error: // Inside a SwiftUI View struct... let cancelled: @MainActor () -> Void var body: some View { ... Button(action: self.cancelled) { Text("Cancel") } // Error here The compiler reports: Converting function value of type '@MainActor () -> Void' to '() -> Void' loses global actor 'MainActor' I originally put that attribute on the cancelled property, because in the passed-in closure, I was doing something that gave me an error about how I had to be on the MainActor.
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2.6k
Sep ’21
Wrapped UIActivityViewController is blank on first showing
Here's the entire app below. On iOS 15, it pops up blank. If you dismiss it and click "Share" again, then it looks right. Is this a bug, or is the code wrong? struct ContentView: View {     @State private var showShare = false     @State private var shareItems: [Any] = []     var body: some View {         VStack {             Text("Test ActivityViewController")             Button("Share") {                 share()             }.sheet(isPresented: $showShare) {                 print("dismissed")             } content: {                 ActivityViewController(activityItems: shareItems)             }         }     }     func share() {         shareItems = ["test"]         showShare = true     } } struct ActivityViewController: UIViewControllerRepresentable {     let activityItems: [Any]     func makeUIViewController(context: Context) -> UIActivityViewController {         let c = UIActivityViewController(activityItems: activityItems, applicationActivities: nil)         return c     }     func updateUIViewController(_ uiViewController: UIActivityViewController, context: Context) {} }
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621
Sep ’21