带有UISplitViewController的UIWindow子类不会旋转

Question

Very easy problem to reproduce. Create a new Master/Detail Application iOS project, and change the AppDelegate to this:

import UIKit

class WindowSubclass: UIWindow { }

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UISplitViewControllerDelegate {

//    var window: UIWindow?
    var window: WindowSubclass? = { WindowSubclass(frame: UIScreen.mainScreen().bounds) }()

Run on iPad simulator/device and start rotating. If the device was in portrait mode when the application was launched, it'll rotate fine. If the application launched in landscape mode, it'll quickly get messed up.

I suspect my problem is in the getter for the window property, but I'm not sure how to resolve it. The line I used seems to be the canonical way of doing it.

Based on answers to similar questions, I have ensured that the window's rootViewController is set to the UISplitViewController and the split view controller's shouldAutorotate() returns true , so that shouldn't be the issue.

Answer 1

Here's a 'maybe' solution.

It seems that when the window property is accessed, and the WindowSubclass instantiated, the screen doesn't really know what orientation it is.

If you add window!.frame = UIScreen.mainScreen().bounds in application(didFinishLaunchingWithOptions:) then it sorts itself out.

Answer 2

I think the reason this is happening is because it's the UIViewController which launches the app. On all other UIViewControllers , my subclass UIWindow rotates fine when I set its rootViewController as the UIViewController that it's being presented on. I'm not sure if this is the intended behavior for some reason or if it's a bug in iOS.