Swift prepareForSegue取消

问题描述

我正在尝试实现登录屏幕，当点击登录时，它会执行segue登录。

I'm trying to implement a login screen, when login is clicked it does the segue "login".

我添加了一个prepareForSegue（）覆盖试图如果登录失败，取消它，但如果失败，我没有看到任何取消segue的方法。

I added a prepareForSegue() override to try to cancel it if the login fails but I don't see any method to cancel the segue if there is a failure.

最好的方法是什么？

推荐答案

您应该覆盖 shouldPerformSegueWithIdentifier 并在登录失败时返回false：

You should override shouldPerformSegueWithIdentifier and return false if login failed:

override func shouldPerformSegueWithIdentifier(identifier: String?, sender: AnyObject?) -> Bool {
    if let ident = identifier {
        if ident == "YourIdentifier" {
             if loginSuccess != true {
                  return false
             }
         }
     }
     return true
}

SWIFT 3更新
现在调用Swift 3方法 shouldPerformSegue

    override func shouldPerformSegue(withIdentifier identifier: String?, sender: Any?) -> Bool {
    if let ident = identifier {
        if ident == "YourIdentifier" {
            if loginSuccess != true {
                return false
            }
        }
    }
    return true
}

//扩展

如果以编程方式调用performSegueWithIdentifier，则不会调用此方法，但不需要调用此方法，您可以将其称为登录成功，否则忽略它：

If you programmatically call performSegueWithIdentifier this method will not be called but it's not need for that, you can call it just your login success, otherwise ignore it:

if loginSuccess {
    performSegueWithIdentifier("login", sender: nil)
}

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