How to set an app's UIWindow color when calling it from ViewController

问题

In the App delegate, it is possible to set an app's UIWindow color as seen in the code.

However, when trying to set an app's UIWindow color to a different color in the ViewController, a call for example to self.window?.backgroundColor = UIColor.blueColor() gets ignored. No errors occur, but no color change occurs either.

Question:

1 - How can I set an app's window color when calling it in the ViewController? Note: I'm not trying to change a View background color, but the UIWindow color which sits behind a View.

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        self.window?.backgroundColor = UIColor.redColor()

        return true

    }

}

回答1:

Try accessing the window through your AppDelegate or UIApplication classes:

if let window = (UIApplication.sharedApplication().delegate?.window)! as UIWindow! {
    window.backgroundColor = UIColor.redColor()
}

if let window = UIApplication.sharedApplication().windows.first as UIWindow! {
    window.backgroundColor = UIColor.redColor()
}

回答2:

For Objective-C you can use this code:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    // your code
    [UIApplication sharedApplication].delegate.window.backgroundColor = [UIColor yourColor]; 

    return YES;
}

回答3:

Swift 5:

if let window = UIApplication.shared.delegate?.window as? UIWindow {
    window.backgroundColor = .red
}

来源：https://stackoverflow.com/questions/35920020/how-to-set-an-apps-uiwindow-color-when-calling-it-from-viewcontroller

标签

ios

swift

uiwindow