extension UIViewController {
    var topbarHeight: CGFloat {
        return
            (view.window?.safeAreaInsets.top ?? 0) +
            (view.window?.windowScene?.statusBarManager?.statusBarFrame.height ?? 0.0) +
            (self.navigationController?.navigationBar.frame.height ?? 0.0)
    }
}

这里有一个简单的答案，可以找到所有iphone的安全区域高度

let window = UIApplication.shared.windows[0]

let SafeAreaHeight = window.safeAreaLayoutGuide.layoutFrame.size.height

在iOS 11中，有一个方法告诉安全区域什么时候发生了变化。

override func viewSafeAreaInsetsDidChange() {
    super.viewSafeAreaInsetsDidChange()
    let top = view.safeAreaInsets.top
    let bottom = view.safeAreaInsets.bottom
}

Swift 5扩展

这可以作为一个扩展，并调用:UIApplication.topSafeAreaHeight

extension UIApplication {
    static var topSafeAreaHeight: CGFloat {
        var topSafeAreaHeight: CGFloat = 0
         if #available(iOS 11.0, *) {
               let window = UIApplication.shared.windows[0]
               let safeFrame = window.safeAreaLayoutGuide.layoutFrame
               topSafeAreaHeight = safeFrame.minY
             }
        return topSafeAreaHeight
    }
}

Extension of UIApplication是可选的，可以是UIView的扩展或者任何你喜欢的，或者更好的全局函数。

对于iPhone 14设备使用如下。

let app = UIApplication.shared
var statusBarHeight: CGFloat = 0.0
let window = app.windows.filter {$0.isKeyWindow}.first
statusBarHeight = window?.windowScene?.statusBarManager?.statusBarFrame.height ?? 0
let topPadding = window?.safeAreaInsets.top ?? 0.0
statusBarHeight = statusBarHeight >= topPadding ? statusBarHeight:topPadding

Swift 5, Xcode 11.4

`UIApplication.shared.keyWindow` 

它将给出弃用警告。" keyWindow "在iOS 13.0中已弃用:不应该用于支持多场景的应用程序，因为它会在所有连接的场景中返回一个键窗口。我用这种方法。

extension UIView {

    var safeAreaBottom: CGFloat {
         if #available(iOS 11, *) {
            if let window = UIApplication.shared.keyWindowInConnectedScenes {
                return window.safeAreaInsets.bottom
            }
         }
         return 0
    }

    var safeAreaTop: CGFloat {
         if #available(iOS 11, *) {
            if let window = UIApplication.shared.keyWindowInConnectedScenes {
                return window.safeAreaInsets.top
            }
         }
         return 0
    }
}

extension UIApplication {
    var keyWindowInConnectedScenes: UIWindow? {
        return windows.first(where: { $0.isKeyWindow })
    }
}