iOS11设备上safeAreaInset的不同返回没有缺口

Question

Currently I am using the following snippet to get the safeAreaInset.top value to set up a constraint for my view.

extension UIDevice {
     var safeAreaInsets: UIEdgeInsets {
         if #available(iOS 11.0, *) {
             if let keyWindow = UIApplication.shared.windows.filter({ $0.isKeyWindow}).first {
                 return keyWindow.safeAreaInsets
             }
         }
         return UIEdgeInsets.zero
     }
}

On iPhone with iOS 12 or above, the safeAreaInsets seems doing fine, returning UIEdgeInsets(20, 0, 0, 0) for device without notch and UIEdgeInsets(47, 0, 34, 0) for device with notch.

But on iOS 11, the safeAreaInset always return UIEdgeInsets(0, 0, 0, 0) for device without notch.

I tried it on different size devices without notch (iPhone7, iPhone8, iPhone8 Plus), and they only return UIEdgeInset(0, 0, 0, 0) on iOS 11 version (11.2, 11.4, etc), but returning the correct UIEdgeInset(20, 0, 0, 0) on other iOS 11+ version. (And on devices with notch, seems they return the correct safeAreaInset UIEdgeInset(47, 0, 34, 0) for all iOS 11 or above version.)

My question is, why safeAreaInset return differently only on iOS 11 device without notch, and what is the appropriate way to get the safeAreaInset.

Answer 1

Declare window in your AppDelegate first like this:

var window: UIWindow?

You can get the safeAreaInsets like this:

let _appDelegator = { return UIApplication.shared.delegate! as! AppDelegate }()

var _safeAreaInsets: UIEdgeInsets {
    get {
        if let window = _appDelegator.window{
            return window.safeAreaInsets
        }else if let vc = _appDelegator.window?.rootViewController{
            return vc.view.safeAreaInsets
        }
        return UIEdgeInsets.zero
    }
}