iphone - 从扩展调用 UIViewController 中的函数

Question

我有一个 UIViewController，它从服务器加载一些 json 数据。如果服务器关闭或用户关闭了数据，我会发出警告告诉用户。这是使用 UIAlertController 完成的。这很好用。所以我把它放到一个扩展中，因为它被所有需要数据的 UIViewControllers 使用。现在 UIAlertController 也有一个 Action 集

警报代码

extension UIViewController {    
func connectionLost(){
    var message = "Your device has lost connection to the server. Check that you have a valid internet connection and then retry."

    let alertController = UIAlertController( title: "Connection Lost",
                                             message: message,
                                             preferredStyle: .alert)
    let retryAction = UIAlertAction(title:"Retry", style: .default, handler: {
        action in

        //call function in the viewcontroller that raised this alert to reload the data
    })
    alertController.addAction(retryAction)
    self.present(alertController, animated: true, completion: nil)
}
}

当用户点击重试按钮时，我想调用 uiviewcontroller 中引发警报的函数。

我尝试在扩展中创建一个委托(delegate)，但很难像在类里面那样连接它。有哪些方法可以从引发警报的 View Controller 中的扩展调用函数？

Answer 1

您应该创建一个 BaseViewController 并使用 Inheritance .它也可能对其他实现有用。

class BaseViewController: UIViewController {

    func onRetryClick() {
        // override to customize or write here the common behaviour
    }
}

class FirstViewController: BaseViewController {
    override func onRetryClick() {
        // do something specific for FirstViewController
    }
}

class SecondViewController: BaseViewController {
    override func onRetryClick() {
        // do something specific for SecondViewController
    }
}

class ThirdViewController: BaseViewController {
    // if you don't override this method, super class (BaseViewController) implementation will be executed
}

extension BaseViewController {    

    func connectionLost(){
        var message = "Your device has lost connection to the server. Check that you have a valid internet connection and then retry."

        let alertController = UIAlertController( title: "Connection Lost",
                                             message: message,
                                             preferredStyle: .alert)
        let retryAction = UIAlertAction(title:"Retry", style: .default, handler: { action in
            self.onRetryClick()
        })

        alertController.addAction(retryAction)
        self.present(alertController, animated: true, completion: nil)
    }
}