Some times, only the preview of SwiftUI view crashes. Both the simulator and the real device don't crash. So we need to do extra works or don't run some methods if the target is a preview.

We can't identify preview from debug, so we add a isPreview variable under debug, and that won't leave the variable in release version.

struct SomeView : View {
    #if DEBUG
    var isPreview = false
    #endif
    var body: some View {
        Text("Hello World!")
            .onAppear {
                #if DEBUG
                if isPreview {
                    return
                }
                #endif
                
                foo()
            }
    }
    
    private func foo() {
        ...
    }
}

struct SomeView_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            SomeView(isPreview: true)
                .previewDevice(PreviewDevice(rawValue: "iPhone SE 2"))
                .previewDisplayName("iPhone SE 2")
            
            SomeView(isPreview: true)
                .previewDevice(PreviewDevice(rawValue: "iPhone 14 Pro"))
                .previewDisplayName("iPhone 14 Pro")
        }
    }
}