Implement extensions for classes on ios based on protocol
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protocol TopUIViewController { func topUIViewController() -> UIViewController? } extension UIWindow : TopUIViewController { func topUIViewController() -> UIViewController? { if let rootViewController = self.rootViewController { return self.recursiveTopUIViewController(from: rootViewController) } return nil } private func recursiveTopUIViewController(from: UIViewController?) -> UIViewController? { if let topVC = from?.topUIViewController() { return recursiveTopUIViewController(from: topVC) ?? from } return from } } extension UIViewController : TopUIViewController { @objc open func topUIViewController() -> UIViewController? { return self.presentedViewController } } extension UINavigationController { override open func topUIViewController() -> UIViewController? { return self.visibleViewController } } extension UITabBarController { override open func topUIViewController() -> UIViewController? { return self.selectedViewController ?? presentedViewController } } |