If you use a TabView in a Preferences scene you get nice looking tabs. If you use a TabView in the main scene, the tabs are plain. Is there a way to fix that? Thanks, Mark

I have seen code where a struct is defined and then in the same file an extension for the same struct is defined. Why not just include the contents of the extension in the original struct definition?

I'm trying to create a custom control similar to a DisclosureGroup. I would like to align the leading edges of "11" and "First". There is a Button preceding "First", but none preceding "11". Bonus question. I'm using SF Symbols for the arrows, but I would like to use the > and V used in DisclosureGroup. Are those symbols available? Thanks, Mark var body: some View { List(items, selection: $selection) { master in HStack { if master.master { Button { if master.master { expanded.formSymmetricDifference([master.id]) } } label: { Image(systemName: expanded.contains(master.id) ? "arrowtriangle.down" : "arrowtriangle.forward") } .buttonStyle(BorderlessButtonStyle()) } Text(master.name) } } .frame(width: 200) }

This morning the Canvas preview on the app I am developing starting displaying "Cannot preview in this file...". The diagnostics display complains: MessageSendFailure: Message send failure for send previewInstances message to agent ================================== |  RemoteHumanReadableError |   |  LoadingError: failed to load library at path "/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib": Optional(dlopen(/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib, 0x0002): tried: '/Users/mark/Library/Developer/Xcode/DerivedData/BoxDesigner-gbhzycedtosmdoetkpwtcpuwawhb/Build/Intermediates.noindex/Previews/BoxDesigner/Products/Debug/MainView.1.preview-thunk.dylib' (no such file), '/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib' (code signature in <D4EED909-712E-3055-B429-BBA7EB77A196> '/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib' not valid for use in process: mapped file has no Team ID and is not a platform binary (signed with custom identity or adhoc?))) The file /Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib is present. I tried deleting the /Users/mark/Library/Containers/com.microenh.BoxDesigner folder and rebuilding. No change.

I have a Mac Mini M1 with OSX Monterey. I just upgraded to 12.4. I'm currently using Xcode 13.4, but I've had this problem for a while now. I have two Acer CB282K monitors. CB282K(2) is connected to the Mini's HDMI port and is configured as the main display. CB282K(1) is connected to a USB-C port via a USB-C / HDMI adapter and is configured as extended. Both monitors appear to be working perfectly. If I hover my mouse over the green button at the top of the most windows, one of the pop up options is "move to CB282K(1)" or "move to CB282K(2)" depending on which monitor is currently displaying the window. This works fine with most if not all of my programs (including Mail and Safari), but not with Xcode. When I first open any window, while the option is there, selecting it does not move the window to the other monitor. However, if I drag the window to the other window, the option works to move the window back and forth between the monitors. If I close the window and re-open it, it is again "locked" to the main display until I drag it. I see this behavior with the first Xcode window I open, with a second Xcode window I open (say I want to view two projects at the same time), or with the Developer Help window. I'm pretty sure that when I started with Xcode last summer, this feature worked, but it has stopped at some point in the past.

While I appreciate the work that Apple puts into the developer documentation, I find it very hard to use. Among other things, I'm looking for a reference (free / paid / online / dead tree) that describes the views available in SwiftUI with the applicable view modifiers and examples of how to use them.

Can someone tell me how Xcode provides the row of images (see above) at the top of the Navigator panel to switch among the various options? It does the same thing with the Inspector panel. Thanks, Mark

I am currently working with XCode 13.3.1 on OSX Monterey 12.3.1 on a Mac Mini M1. I have written some programs in Swift for personal use using a personal team certificate. I haven't paid the $99. Every couple of weeks or so, some of my programs will pop up a message saying "This Program Could Harm Your Mac" and won't let me run it when I try to launch them. It seems I have to recompile it and then it will work for a few more weeks. Other programs have run for several months. The programs are using Sandbox and Hardened runtime. Someone suggested that I try compiling the program without a certificate. I did that last night and the program ran. But this morning when I launched the program, I got a message that the program had unexpectedly quit. The "report" message said something about a code signature. FWIW, I am copying the program to my Applications folder.

func zoomOne() { region.span.latitudeDelta = 10_000 region.span.longitudeDelta = 10_000 } func zoomIn() { region.span.latitudeDelta /= 2 region.span.longitudeDelta /= 2 } func zoomOut() { region.span.latitudeDelta *= 2 region.span.longitudeDelta *= 2 } My MacOS app has three methods for adjusting the zoom on a MapKit map display. Each is tied to a separate view Button. zoomIn() and zoomOut() work as expected, but when the program calls zoomOne(), Xcode breaks and reports a runtime issue in the Issue Navigator: NSHostingView is being laid out reentrantly while rendering its SwiftUI content. This is not supported and the current layout pass will be skipped. As a fix, I tried embedding the zoomOne() region update in a DispatchQueue.main.async closure, but it still failed with the same issue. Thanks, Mark

.commands{ SidebarCommands() } If I add the above to a MacOS app, the program gains a Show Sidebar / Hide Sidebar menu option on the View menu. I'd like to add a button to show or hide the sidebar such as the one in Xcode, but I can't find a way to do it? I would have thought that there would be a simple framework call, but my internet searches haven't turned up anything. I also like the way that Xcode places the Hide Sidebar button on the sidebar, but when the sidebar is hidden, the Show Sidebar button is on the left side of the window. Has any one figured out how to do this with SwiftUI?

I have an app that displays a MapKit map with a Text as an a MapAnnotation. When the map is first displayed, the map is centered on the coordinates of the MapAnnotation and once things settle down, the CPU usage reported by Xcode's Debug Navigator goes to 0%. If the map is dragged or zoomed so that the MapAnnotation is not at the center, the CPU usage goes up during the motion, but does not go back to 0%, but settles down to a few per cent. If you look closely at the map, you can sometimes see that the MapAnnotation is vibrating. Other map features do not appear to move. I assume that the MapAnnotation is not tied to a fixed map location as are the map features and if the MapAnnotation is not at the center, its display position needs to be constantly recalculated.

I'm looking for some in-person contacts to help me learn MacOS programming. I'm willing to share what I've learned. Thanks, Mark

I have a MacOS app that displays a MapKit Map on the main scene. The user can drag the map around with the mouse and the motion is smooth, until I enable the Settings scene. With the Settings scene enabled, the map doesn't follow the mouse but moves when the mouse is released. If I replace the Settings scene with a "Hello, World" view, the map dragging is fine. var body: some Scene { WindowGroup { LicenseLookupView(fccData: fccData) .navigationTitle(title) } Settings { FCCDatabaseSettings(fccData: fccData) } } I put a print statement in the constructor to the Setttings scene and the program prints multiple times as the map is dragged, so it appears that even though the Settings scene is not displayed to the user, it is being recreated every time the main Scene is updated. Is there a way to keep that from happening and only build the Settings scene when it is going to be shown to the user? As a comparison, the Preferences... dialog for Xcode is complex, yet it doesn't impact the performance of the app. Of course, Xcode may not be written in SwiftUI. Thanks in advance, Mark

I used the Xcode template to create a Mac App. I then modified ContentView.swift import SwiftUI import MapKit struct ContentView: View {     @State private var region = MKCoordinateRegion( center: CLLocationCoordinate2D( latitude: 0.0, longitude: 0.0), span: MKCoordinateSpan( latitudeDelta: 0.5, longitudeDelta: 0.5))     var body: some View {         Map(coordinateRegion: $region) } } struct ContentView_Previews: PreviewProvider {     static var previews: some View {         ContentView()     } } When I run this code, Xcode reports a runtime error: Modifying state during view update, this will cause undefined behavior. It is reported on Thread 1. This is identified with a purple warning in the issue navigator, but there is no indication of the location of the error in the source code editor. The actual map coordinates don't matter. I get the same error with different coordinates. Xcode 13.3.1 OSX Monterey 12.3.1 Mac Mini M1 P.S. When I cut the example code above from Xcode and pasted it into this message, it added extra line breaks between each line (which I manually removed). Is there a way to have the code paste as it was in Xcode? P.P.S. When I listed the software and hardware info, If I don't make it a bulleted list, the ended up being displayed on one line. If I put blank lines between them, the blank lines are displayed. Is there any way to make a vertical list without bullets?

I've copied a couple of tutorial Mac OS apps using MapKit. One uses SwiftUI, the other AppKit. Both initially display a map and allow the user to pan and zoom with the mouse. According to XCode's debug navigator, once the user has stopped panning or zooming, the CPU usage goes to 0%. Both apps allow the user to enter a location and add a MapAnnotation to the map. On the AppKit version, once the annotation is added, the CPU usage drops back to 0%, but on the SwiftUI version, the CPU usage remains around 5 - 15%. If you look closely at the SwiftUI version, you can see the annotation vibrating by a pixel or so on the display. It seems to me that the display is being constantly updated. If the annotation is removed, the CPU usage goes back to 0% I placed a breakpoint in the code that draws the annotation in the SwiftUI version. When adding an annotation, the breakpoint is hit twice, but then no more, so I don't think the CPU is spending time in the Swift code. Xcode 13.3.1 OSX Monterey 12.3.1 Mac Mini M1