使用shouldPerformSegueWithIdentifier在swift中取消segue

Question

我有一个功能,检查登录是否正确.如果没问题,我会显示下一个屏幕.如果用户不正确,我取消segue并显示警告.

问题出现的原因是当我在shouldPerformSegueWithIdentifier函数中调用此函数时,我给布尔变量赋值(如果用户是否正确),那么shouldPerformSegueWithIdentifier的返回值就是这个布尔值.问题是它没有采用该值并保持默认值.这是我的代码:

override func shouldPerformSegueWithIdentifier(identifier: String!, sender: AnyObject!) -> Bool {

    var userIsCorrect = false //THIS IS THE BOOLEAN

    if identifier == "fromLogInToGetIn" {

        self.loginRequest("http://myurl.com",

            withParams: ["email":"email@email.com","password":"password"])

        {

            (succeeded: Bool, msg: String) -> () in

            var alert = UIAlertView(title: "Success!", message: msg, delegate: nil, cancelButtonTitle: "Okay.")

            if(succeeded) {

                if msg == "0"

                {

                    userIsCorrect = false // BOOLEAN DOES NOT TAKE THE VALUE

                    alert.title = "Error"

                    alert.message = "Incorrect user"

                }

                else

                {

                    userIsCorrect = true // BOOLEAN DOES NOT TAKE THE VALUE

                }

            }

            else {

                userIsCorrect = false // BOOLEAN DOES NOT TAKE THE VALUE

                alert.title = "Error"

                alert.message = "Something is wrong"

            }

            // Move to the UI thread

            dispatch_async(dispatch_get_main_queue(), { () -> Void in

                // Show the alert

                if userIsCorrect == false

                {

                    alert.show()

                }

            })

        }

    }

    return userIsCorrect // ALWAYS RETURN DEFAULT VALUE

}

提前致谢.

Answer 1

只需将attache segue与ViewController A连接到ViewController B,假设segue的名称为mySegue1,假设单击了Login Button.检查一切是否正确.如果它是正确的那么,

         self.performSegueWithIdentifier("mySegue1", sender: self)