How to adapt ios13 statusbar?

Use UIStatusBarManager to get the statusBar height in iOS13:

UIStatusBarManager *manager = [UIApplication sharedApplication].keyWindow.windowScene.statusBarManager;

CGFloat height = manager.statusBarFrame.size.height;

SceneDelegate.swift file

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

    guard let windowScene = (scene as? UIWindowScene) else { return }
    if let statusBarFrame = windowScene.statusBarManager?.statusBarFrame {
        print(statusBarFrame)
    }
}

As Peter noted on Tamarous's answer, the keyWindow property is deprecated, however on the assumption you're using a single window you can alternatively use:

CGSize statusBarSize = [UIApplication sharedApplication].windows.firstObject.windowScene.statusBarManager.statusBarFrame.size

If you needed to access the nth window, you could do so in a similar manner:

NSInteger i = 0;
CGSize statusBarSize = [UIApplication sharedApplication].windows[i].windowScene.statusBarManager.statusBarFrame.size;

Solution:

let window = UIApplication.shared.windows.filter {$0.isKeyWindow}.first
lazy var statusBarHeight = window?.windowScene?.statusBarManager?.statusBarFrame.height ?? 0

Explanation :

You can't use window in a let because it doesn't exist when that property is created because it belongs to self. So at init, self isn't complete yet. But if you use a lazy var, then self and its property window will be ready by the time you need it.

Or another solution use singleton:

struct AppConstants {
    static let window = UIApplication.shared.windows.filter {$0.isKeyWindow}.first
    static let statusBarHeight = window?.windowScene?.statusBarManager?.statusBarFrame.height ?? 0
}