Swift 方法交换：实现应用方向控制

要在 Swift 中交换一个方法，你需要使用method_exchangeImplementations 方法。首先，你需要创建一个扩展来添加新的方法：

extension UIApplicationDelegate {
    @objc func my_application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
        // 添加你想要的逻辑
        return .portrait
    }
}

然后，在application(_:supportedInterfaceOrientationsFor:) 方法中，使用method_exchangeImplementations 方法交换原始方法和新方法：

class AppDelegate: UIResponder, UIApplicationDelegate {

    // ...

    func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
        let originalSelector = #selector(application(_:supportedInterfaceOrientationsFor:))
        let swizzledSelector = #selector(self.my_application(_:supportedInterfaceOrientationsFor:))

        let originalMethod = class_getInstanceMethod(type(of: self), originalSelector)!
        let swizzledMethod = class_getInstanceMethod(type(of: self), swizzledSelector)!

        method_exchangeImplementations(originalMethod, swizzledMethod)

        // 调用新方法
        return self.my_application(application, supportedInterfaceOrientationsFor: window)
    }

    // ...
}

这样，你就可以在新方法中添加你想要的逻辑，并在交换后调用新方法。