swift - 为什么完成不起作用？完成问题

Question

为什么完成不起作用？

警报出现后，它不会过渡到另一个 viewController

self.present(self.alertController2, animated: true, completion:  {                          
    self.performSegue(withIdentifier:"goToLogin", sender: self)
})

Answer 1

Self.present 用于将此操作添加到 View 中。您需要将此代码添加到您的 handler handler mean It means what will I will I do when you click OK

let alertbutton = UIAlertAction(title: "OK", style: .destructive, handler: { 
(UIAlertAction) in
            self.performSegue(withIdentifier: "your id", sender: self)
        })

完整示例:

let alert = UIAlertController(title: "Its empty", message: "Going another view", preferredStyle: .alert)
        let alertaction = UIAlertAction(title: "OK", style: .destructive, handler: { (UIAlertAction) in
            self.performSegue(withIdentifier: "your segue id", sender: self)
        })
        alert.addAction(alertaction)
        self.present(alert, animated: true, completion: nil)