Hi,I'm trying to port this to Swift. https://developer.apple.com/documentation/metal/hello_triangleTo get it to run I had to add the following line to the renderer class. Any idea why it's not needed in the Objective-C version? pipelineStateDescriptor.depthAttachmentPixelFormat = metalView.depthStencilPixelFormatWithout it I get an error: -[MTLDebugRenderCommandEncoder validateFramebufferWithRenderPipelineState:]:1232: failed assertion `For depth attachment, the render pipeline's pixelFormat (MTLPixelFormatInvalid) does not match the framebuffer's pixelFormat (MTLPixelFormatDepth32Float).'Rob

I'm wondering how SwiftUI updates work in connection with ObservableObjects. If a SwiftUI View depends on an `ObservableObject`, the object's `objectWillChange` publisher fires, and SwiftUI learns about the change, before the change happens. At this point, SwiftUI can't re-render a View, right? Because the new properties aren't there yet. So what does SwiftUI do? Does it schedule the change for later? That doesn't make sense either - how can it know when the object will be ready to be used in a new rendering of the UI? ~ Rob

Hi,I have a lot of UIViews where the compiler forces me to add an init(coder:) initializer, like this:class FooView : UIView /* or a UIView subclass */ { ... required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } ... }It claims it's required but my program runs fine without it. I do not create the views from an archive.This makes me wonder if something is wrong here with the design of the library, or the concept of a 'required' initializer. What do people think? Does it make sense or is this a wart? If so, can it be fixed?Rob

After updating to 12.5, I now get an error trying to run my unit tests. This is for a macOS app. dyld: warning: could not load inserted library '/[...]/DerivedData/[...]/Contents/Frameworks/libXCTestBundleInject.dylib' into hardened process because no suitable image found.  Did find: /[...]/libXCTestBundleInject.dylib: code signature in (/[...]/libXCTestBundleInject.dylib) not valid for use in process using Library Validation: mapped file has no Team ID and is not a platform binary (signed with custom identity or adhoc?) Anyone else face and fix this, or understand what it is? I changed the "Signing Certificate" in my test target to "Sign to Run Locally" (from "Development") to see if that would help. It didn't fix it.

I've been using protocols to help model a hierarchy of different object types. As I try to convert my app to use SwiftUI, I'm finding that protocols don't work with the ObservableObject that you need for SwiftUI models. I wonder if there are some techniques to get around this, or if people are just giving up on "protocol oriented programming" when describing their SwftUI models? There is example code below. The main problem is that it seems impossible to have a View that with an model of protocol `P1` that conditionally shows a subview with more properties if that model also conforms to protocol `P2`.For example, I'm creating a drawing/painting app, so I have "Markers" which draw on the canvas. Markers have different properties like color, size, shape, ability to work with gradients. Modeling these properties with protocols seems ideal. You're not restricted with a single inheritance class hierarchy. But there is no way to test and down-cast the protocol...protocol Marker : ObservableObject { var name: String { get set } } protocol MarkerWithSize: Marker { var size: Float { get set } } class BasicMarker : MarkerWithSize { init() {} @Published var name: String = "test" @Published var size: Float = 1.0 } struct ContentView<MT: Marker>: View { @ObservedObject var marker: MT var body: some View { VStack { Text("Marker name: \(marker.name)") if marker is MarkerWithSize { // This next line fails // Error: Protocol type 'MarkerWithSize' cannot conform to 'MarkerWithSize' // because only concrete types can conform to protocols MarkerWithSizeSection(marker: marker as! MarkerWithSize) } } } } struct MarkerWithSizeSection<M: MarkerWithSize>: View { @ObservedObject var marker: M var body: some View { VStack { Text("Size: \(marker.size)") Slider(value: $marker.size, in: 1...50) } } }Thoughts?

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) {} }

I'm surprised this simple code still doesn't work on iOS 13.3 / Xcode 11.3. On my iPhone SE it's almost all off screen.It's just two pieces of text, side by side, and two pickers, side by side. Anyone know a workaround? struct ContentView: View { @State var choice: Int = 10 @State var choice2: Int = 10 var body: some View { return VStack { HStack { Text("Some text here") Spacer() Text("Foo baz") } HStack { Picker(selection: self.$choice, label: Text("C1")) { ForEach(0..<10) { n in Text("\(n) a").tag(n) } } Picker(selection: self.$choice2, label: Text("C2")) { ForEach(0..<10) { n in Text("\(n) b").tag(n) } } } } } }

Hi,I had a document-based iOS app working, but want to change it so it saves to a package. Seems like it's better when big chunks of a file may not be changing. In Xcode, under the Target > Info > Exported UTI > Conforms To, I had: "public.data, public.content". If I change that to "com.apple.package", then I can't open my old files to upgrade them. But if I *add* "com.apple.package", then the app opens both kinds as desired. I wonder if having it conform to all three of those types is going to cause other problems.Rob

Does anyone use the new hierarchical data List (ie, OutlineGroup) with a model where the tree data changes? I'm on Big Sur beta. I have code like this: List([treeRoot], children: \.children) { item in ... Say the treeRoot (observed object) gets a new child. The view tries to re-render and fails: 2020-09-21 ... [General] NSOutlineView error inserting child indexes <_NSCachedIndexSet: 0x600000760000>[number of indexes: 1 (in 1 ranges), indexes: (3)] in parent 0x0 (which has 1 children).

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.

I have a button to restore purchases in my app. It calls AppStore.sync() as suggested by sample code. I'm testing in the sandbox, I put my device in airplane mode, and it throws StoreKitError.userCancelled. That's odd. Anyone else see this? I'd like to show an error alert popup to the user here, but I can't differentiate between this an a real userCancelled.

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.

Here's a simple demo. I run it on macOS 12.1, compiled with Xcode 13.2. struct ContentView: View {     var body: some View {         VStack {             Text("ee")             Text("eé") Text("e\u{E9}") // "e with acute"             Text("ee\u{301}") // "combining acute"         }.font(.custom("Avenir", fixedSize: 18))          .padding(20)     } } In the 4rd one, the "e" is rendered in the wrong size/font. Screenshot: Other fonts do not have the problem. For example, "Avenir Next" and "Helvetica". Is there a way (in code) to tell which fonts can handle combining chars? Is this a bug? I notice the same thing happens when I use Core Text to draw the strings at a low level. So it's not just SwiftUI. In TextEdit, if have Avenir font, type "option-e" + "e" I get a nice letter. Maybe TextEdit is doing what Xcode did in the second line, and using the "e with acute" unicode character.

I'm working on a drawing and painting program. When I turn my iPad, I detect the screen change and keep the drawing stable, while allowing the toolbars and things to rotate. But SwiftUI creates a disorienting animation of the main canvas anyway. Is there a way to shut that off?

Hi,I need to save and load metal textures to a file. Example code below is below. I'm noticing the RGB values are changing as it gets saved and reloaded again.metal texture pixel: RGBA: 42,79,12,95after save and reload: 66,88,37,95I thought it might be a colorspace issue, but the colorspaces I’ve tried all had the same problem. `genericRGBLinear` got close, but there’s got to be a way to save the RGB data and get it back exactly. ?thanks,RobCode:// saving... let ciCtx = CIContext() let ciImage = CIImage(mtlTexture: metalTexture, options: [:]) [ … transfrom to flip y-coordinate …] let colorSpace = CGColorSpaceCreateDeviceRGB() let cgImage = ciCtx.createCGImage(ciImage, from: fullRect, format: kCIFormatRGBA8, colorSpace: colorSpace)! let imageDest = CGImageDestinationCreateWithData(mData, kUTTypePNG, 1, nil)! CGImageDestinationAddImage(imageDest, cgImage, nil) CGImageDestinationFinalize(imageDest) // loading... let src = CGImageSourceCreateWithData(imgData, nil) let img = CGImageSourceCreateImageAtIndex(src, 0, nil) let loader = MTKTextureLoader(device: self.metalDevice) let texture = try! loader.newTexture(cgImage: img, options: [:])