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I'm seeing some weird behavior with conditional compilation when I use a build configuration other than "Debug" or "Release", and I'm wondering if I'm doing something wrong or if this is an Xcode bug.
The setup
Xcode version: 15.3
I have a simple SwiftUI view that takes in a model and displays an attribute of the model.
struct ContentView: View {
let model: Model
var body: some View {
VStack {
Text("Name: \(model.name)")
}
.padding()
}
}
In the model file, I have the struct definition, but also an extension that defines some sample data for use in SwiftUI previews:
struct Model {
let id: String
let name: String
}
#if DEBUG
extension Model {
static let example = Model(
id: "50fef362-f53d-4ded-9168-b887ff62e59d",
name: "John Doe"
)
}
#endif
And finally, I have a preview provider that uses this sample data:
#Preview {
ContentView(model: Model.example)
}
Normal behavior
With the default "Debug" build configuration, this works just fine. There are no compilation errors, and the preview renders as expected.
The issue
Start off by changing the name of the build configuration to, e.g. "DebugDev"
Now I start seeing seeing a mis-match between what happens and what Xcode tells me is happening.
The code still compiles and runs, and the SwiftUI preview still works, but Xcode is displaying things as if it doesn't compile.
Xcode formats the conditionally compiled code with a lower opacity color as if DEBUG isn't defined:
In the view file, I now see a compilation error when referencing the conditionally-compiled code:
Autocomplete doesn't work when trying to reference the conditionally compiled code
Additional details/observations
I have confirmed that the DEBUG active compilation condition is still defined in the build settings. All I've done is change the name of the build config
I was initially thinking this might have something to do with the fact that this appears in a preview provider, since those are treated a bit differently, but the same thing happens if I reference the conditionally compiled code directly in the view class
Another theory: since I was referencing conditionally compiled code from code that wasn't conditionally compiled, maybe Xcode was trying to tell me that wasn't valid. So, I tried placing the code that calls the conditionally compiled code (in this case, the view class) inside an #if DEBUG. This does get rid of the displayed compilation error, but auto-complete still doesn't work, and the whole class is displayed with the lower-opacity font.
Help?
I feel like I must be missing something. The only alternative I can think of is that Xcode has some logic hard-coded with the default "Debug" build config, and that would be...just silly.
Post not yet marked as solved
With the newest version of Xcode (15.3) I cannot get Preview to load and am getting the following error:
HumanReadableSwiftError
CancellationError: CancellationError()
I'd had this same issue a few months ago and opening up an older project's previews and then opening the project I was working on would allow Preview to show.
The last few weeks I've not been getting this error and after 3 or 4 days not being in Xcode I'm getting this same error again.
I'm relatively new to Xcode and Swift so not being able to load the darn preview and work through tutorials after seemingly doing the exact same thing I've been doing for months is quite ridiculous and frustrating.
Any ideas on how to resolve this issue would be greatly appreciated.
Post not yet marked as solved
On May 1 I started to see this image instead of watch UI preview. It worked well before. I didn't update Xcode, neither I deleted or installed any new simulator OS. It was harmful to my work, since simulator download is 4GB and I need to wait when it downloads, instead of reviewing PRs and closing tasks.
Did anyone had the same issue? Do you know how to prevent it?
Post not yet marked as solved
So like the title says, when I start up Xcode the preview won;t work till I run a debug session using the simulator.
Sometimes the debug session is unable to start the simulator, which I can start manually then run a debug session.
Once all the above is done, preview works.
Any idea what is causing this behavior?
Post not yet marked as solved
SwiftUI Preview Don't work.
Progress Preparing iPhone Simulator for Previews.
SwiftUI
Xcode version 13.0
macOS Big Sur version 11.6
Post not yet marked as solved
The Build for Previews builds all my targets including the test targets. Is there a way to configure the relevant targets? I do not see an option in the schema editor, and disabling Find Implicit Dependencies has no effect either.
Post not yet marked as solved
Hi All,
I have been using Xcode for less than 5 months.
Recently I get a problem that my previews does not load, even when I created a new project on a local disk.
The Project builds, but the preview does not.
The error I saw from the Diagnostics window is as below
== PREVIEW UPDATE ERROR:
HumanReadableSwiftError
CancellationError: CancellationError()
Post not yet marked as solved
I referred to the code provided in the article Adding and Editing Persistent Data in Your App in the SwiftData documentation and tested the "/PreviewHelper" approach. I found that if a model class contains a property of a struct, and that struct includes a Set property or an Array property, the Preview would throw an error. Here is an example of the model:
@Model
class Book {
// ...
var someStruct: SomeStruct
// ...
}
struct SomeStruct: Codable {
// ...
var someCollection: Set<Int>
// ...
}
In actuality, this model can run and store data without any issues, but it fails to run in the Preview. Is there a problem with the implementation of this Preview or is there any other reason? Are there better ways to perform Preview in SwiftData?
Post not yet marked as solved
Hi,
I have had this issue since I started working again in iOS this year with Xcode 15.
What happened to the SwiftUI Previews?
My problem is that they are stuck forever in the Loading screen "Preparing iPhone Simulator for Previews".
I now test the code on the actual Simulator and waiting for Xcode 16 to fix this.
The characteristics of my project are:
Using Swift Package Manager (10+ dependencies)
Using Unit Tests and Test Plans.
Using macOS Ventura (reverted from Sonoma because it's even worse)
Macbook Air M1 - 16GB of RAM.
I have tried everything including:
Erasing derived data.
Restarting.
Reinstalling the whole computer.
Reverting Sonoma to Ventura.
Reverting Xcode 15.2 to 15.1 and 15.0.1.
Using Previews_Provider and #Previews {}
Using completely empty projects to test previews.
Please help.
Thanks
I have an iOS app by using a swift package to hold most of the logic. However, the previews of SwiftUI views often fail with following error:
HumanReadableSwiftError
BuildError: failedToGenerateThunkInfo(Error Domain=com.apple.xcbuild Code=19 "could not generate preview info: noTargetBuildGraph" UserInfo={NSLocalizedDescription=could not generate preview info: noTargetBuildGraph})
To reproduce this, please clone https://github.com/pointfreeco/isowords and check for preview of ChangelogView.
Post not yet marked as solved
Recently my live preview canvas on Xcode recently stopped accepting my keyboard inputs out of the blue when I type in a textField. Has this bug been addressed? I'm on iOS sim 17.4, Xcode 15.3
Post not yet marked as solved
I am not able to use swiftUI preview in my project.
i have attached the diagnosed report for the same.
Please update.
previews_diagnostics_summary.txt
Post not yet marked as solved
Sorry about my English, I'm using a translator.
I'm taking a programming course with Swift in Xcode and one of the steps is to drag a control from the library into the view to place it below another control (both are "text").
In the preview, there is a text in the center of the mobile screen.
In the video, open the library window with Shift + Command + L; then drag a "text" control to the preview that simulates a mobile phone and a stripe appears below the text control that I mentioned before, which means that that text will be placed below it. If you put it on top, then the line appears on top and the same if you put it on the sides.
I have the option that appears below the phone, the one that says "Selectable", activated, so that I can select what I want in that phone simulation.
The fact is that when I drag the text control from the library and try to put it below or in another position with respect to the text that already exists, it does nothing. The stripes do not appear, nor do you set the control.
What could it be due to? I am using Xcode 15.3
Thank you.
Post marked as Apple Recommended
Hi guys,
I am migrating my widgets to iOS 17 and because I already manage my layout margins, I just want to disable to new built-in widget content margins.
I did it by using ".contentMarginsDisabled()" on the WidgetConfiguration and it works fine at run time.
WIDGET CODE
struct MyWidget: Widget {
let kind: String = "MyWidget"
var body: some WidgetConfiguration {
return IntentConfiguration(kind: kind, intent: MyWidgetIntent.self, provider: WidgetProvider<MyWidgetIntent>()) { entry in
WidgetView<MyWidgetIntent>(entry: entry)
}
.configurationDisplayName("My Widget")
.supportedFamilies([WidgetFamily.systemMedium])
.contentMarginsDisabled() // <-- HERE
}
}
RESULT
Nevertheless, when previewing the WidgetView in a WidgetPreviewContext I didn't find anyway to disable the content margins (because manipulating directly the view and not a WidgetConfiguration).
PREVIEW CODE
struct MyWidget_Previews: PreviewProvider {
static var previews: some View {
WidgetView<MyWidgetIntent>(entry: WidgetEntry<MyWidgetIntent>())
// .padding(-16) Need to add this negative padding to disable margin
.previewContext(
WidgetPreviewContext(family: .systemMedium))
}
}
Do you know how to disable the content margins for widget preview?
Post not yet marked as solved
Preview Canvas in The editor stopped showing up. I closed it and did everything I saw on the forum, but it still did not work. I also noticed that in some SwiftView it shows the preview, but it does not the same with the others.
Post not yet marked as solved
Hi all,
I am trying to create a widget for my app but I cannot use the Preview feature of Xcode.
Xcode enters a build loop and builds the project over and over. There is no error or message. There is only a loading spinner and lots of build.
It doesn't matter how much time I wait, it never finishes.
I tried to clean the build folder, delete all preview simulators, quit, and reopen the XCode but nothing helped.
Post not yet marked as solved
Following article Creating a widget extension on developer.apple.com (https://developer.apple.com/documentation/widgetkit/creating-a-widget-extension) I encountered a problem with XCode preview: it shows an error with message
| RemoteHumanReadableError: Failed to launch agent
| No plugin is registered to launch the process type widgetExtension.
Can someone help me?
macOS 13.4
XCode 14.3.1
Post not yet marked as solved
Summary
When trying to display SwiftUI previews, building the previews may fail with the following error:
Linking failed: linker command failed with exit code 1 (use -v to see invocation)
ld: warning: search path '/Applications/Xcode.app/Contents/SharedFrameworks-iphonesimulator' not found
ld: warning: Could not find or use auto-linked framework 'CoreAudioTypes': framework 'CoreAudioTypes' not found
Note that may app does not use CoreAudioTypes.
Observation
This issue seems to occur when two conditions are met:
The SwiftUI view must be located in a Swift Package
Somewhere in either the View or the #Preview a type from another package has to be used.
Say I have to packages one named Model-package and one named UI-Package. The UI-Package depends on the Model-Package. If I have a SwiftUI view in the UI-Package that uses a type of the Model-Package either in the View itself or in the #Preview, then the described error occurs. If I have a View in the UI-package that does not use a type of the Model-Package anywhere in its View or #Preview then the SwiftUI Preview builds and renders successful.
I created a bug report: FB13033812
Post not yet marked as solved
Hello! I'm studying swift in college now, and have encountered a problem previewing my code using canvas. Here's part of the code:
struct ContentView: View {
......(omitted)
var body: some View{
ScrollView{
cards
Spacer()
cardsAdjuster
}
}
The canvas panel looks all right with the line "ScrollView", as the image shows, with the only problem that "cardsAdjuster" moves with the cards.
But if I remove the line "ScrollView", the panel went wrong:
As the image displays, all parts of body are displayed separately, and I can't find any setting options to merge them. (Take a look at the top of the screenshot)
The problem is also found on my classmate's Xcode 12 running on macOS Monterey.
Looking forward to your reply and thoughts. Thank you all!!
Post not yet marked as solved
I am new to Xcode and trying to learn and having issues with errors it seems. I believe the problem is specifically with my code not being able to be displayed on the example iPhone on the right hand side of the screen. Here are the 2 errors I receive below. The codes at the very bottom are red on my screen so I am guessing those are what is most important out of all of this.
Thanks and please let me know if I can answer any additional questions regarding this.
Ld /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Products/Debug-iphonesimulator/Playground.app/Playground normal (in target 'Playground' from project 'Playground')
cd /Users/tward/Desktop/Playground.swiftpm
/Users/tward/Downloads/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -Xlinker -reproducible -target x86_64-apple-ios15.2-simulator -isysroot /Users/tward/Downloads/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator16.4.sdk -L/Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/EagerLinkingTBDs/Debug-iphonesimulator -L/Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Products/Debug-iphonesimulator -L/Users/tward/Downloads/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/lib -F/Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/EagerLinkingTBDs/Debug-iphonesimulator -F/Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Products/Debug-iphonesimulator -F/Users/tward/Downloads/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/Frameworks -iframework /Users/tward/Downloads/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/Frameworks -iframework /Users/tward/Downloads/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator16.4.sdk/Developer/Library/Frameworks -filelist /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/Playground.build/Debug-iphonesimulator/Playground.build/Objects-normal/x86_64/Playground.LinkFileList -Xlinker -rpath -Xlinker @executable_path/../lib -dead_strip -Xlinker -object_path_lto -Xlinker /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/Playground.build/Debug-iphonesimulator/Playground.build/Objects-normal/x86_64/Playground_lto.o -Xlinker -export_dynamic -Xlinker -no_deduplicate -Xlinker -objc_abi_version -Xlinker 2 -fobjc-link-runtime -L/Users/tward/Downloads/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator -L/usr/lib/swift -Xlinker -add_ast_path -Xlinker /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/Playground.build/Debug-iphonesimulator/Playground.build/Objects-normal/x86_64/Playground.swiftmodule -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __entitlements -Xlinker /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/Playground.build/Debug-iphonesimulator/Playground.build/Playground.app-Simulated.xcent -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __ents_der -Xlinker /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/Playground.build/Debug-iphonesimulator/Playground.build/Playground.app-Simulated.xcent.der -Xlinker -no_adhoc_codesign -Xlinker -dependency_info -Xlinker /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Intermediates.noindex/Playground.build/Debug-iphonesimulator/Playground.build/Objects-normal/x86_64/Playground_dependency_info.dat -o /Users/tward/Library/Developer/Xcode/DerivedData/Playground-aoepzfpfzcxxqggglpllgxkoywsr/Build/Intermediates.noindex/Previews/Playground/Products/Debug-iphonesimulator/Playground.app/Playground
ld: entry point (_main) undefined. for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
nivektric.
