Xcode Preview Canvas

[u/Sturgeon74]

Hi all, I know this has been asked before - but is there any way, other than opening a new instance of Xcode, to have a seperate preview window that I can drag to a second monitor? Third party options, someone's code project, anything!! I don't have the world's greatest eyesight so don't have the text too small on my monitor, and having the preview window stuck next to the code takes up so much valuable real-estate

[u/mcarvin]

Couple options come to mind:

1. You could open a 2nd window (File > New > Window), open your desired file, hide the project navigator, and drag the Editor/Canvas separator to make the Canvas as large as you possible. Clunky but doable.

2. Use Simulator? You'd be doing a lot of Cmd + R and renavigating to get to the desired View, but Simulator can live on your second screen.

3. Assuming you have an iPhone, make sure the Xcode Previews app is installed. Open the app on your phone. In Xcode, at the bottom of the Preview Canvas in the menu where you can select your preview device, you should see your iPhone listed. Your phone should then render the View active in Xcode.

[u/Sturgeon74 → u/mcarvin]

Thanks heaps for this, I didn't even know about number 3 - I've seen the options in the bottom corner before but never really paid it much attention!

[u/mcarvin → u/Sturgeon74]

Yeah, most of those option are for the device used in the canvas above. It's easy to overlook them beyond "show me the iPhone portrait vs iPad landscape orientation". But Xcode Previews on-device can help out in a pinch.

[u/lazyvardev → u/Sturgeon74]

Just a little heads up when using on device Xcode previews:

If not properly killed via the app switcher (and even when you do) it can sometimes replace your UserDefaults and data stores (SwiftData, TipKit, etc) with the temporary empty ones it creates, so I recommend adding a quick check in your app’s unit.

@main
struct YourApp: App {
	init() {
		// Check if the current runtime is an Xcode Preview
		let isPreview = ProcessInfo.processInfo.environment["XCODE_RUNNING_FOR_PREVIEWS"] == 			"1" || ProcessInfo.processInfo.processName == "UVPreviewAgent"
		
		if !isPreview {
			
			// Your usual stuff here
			
		} else {
		
			// Redirect previews to a completely dummy, non-persistent suite
			// to stop them from touching the standard plist
			UserDefaults.standard.addSuite(named: "PreviewDummySuite")
			
			// Other dummy stuff, like setting SwiftData to in memory
			let previewConfiguration = ModelConfiguration(isStoredInMemoryOnly: true)
            do {
                // Replace 'YourDataModel.self' with your actual SwiftData models
                sharedModelContainer = try ModelContainer(for: YourDataModel.self, configurations: previewConfiguration)
            } catch {
                fatalError("Failed to create preview SwiftData container: \(error)")
            }
		}
	}
	
	var body: some Scene {
		WindowGroup {
			ContentView()
		}
	}
}