UIAlertview委托方法未在子视图控制器中调用 [英] UIAlertview Delegate Method not calling in Child View Controller

问题描述

我有两个控制器

VC A-> Parent和VC B-> Child

警报视图委托方法，即

func alertView(View: UIAlertView!, clickedButtonAtIndex buttonIndex: Int){}

在VC A中声明.

当我单击警报按钮时，未调用VC B委托方法显示警报时.

When i display alert from VC B delegate method is not called on alert button clicked.

推荐答案

请按照下列步骤操作:

1. 在VC-B中创建一个协议:

protocol AlertViewProtocol:class {
    func alertView(View: UIAlertView!, clickedButtonAtIndex buttonIndex: Int)
}

在VC-B类中添加 var 为:

var delegate: AlertViewProtocol?

在VC-B的任何类方法中使用委托将数据发送到接收方法(即VC-A的任何方法)，该方法是采用协议的任何方法.请遵循以下模式使用委托:

Use the delegate in any class method of VC-B to send the data to the receiving method (i.e. any method of VC-A), which is any method that adopts the protocol. Follow this pattern to use the delegate:

delegate?.alertView(View: UIAlertView!, clickedButtonAtIndex buttonIndex: Int)
// Above statement is like a method calling (on delegate var), use your parameters accordingly

在接收类(此处为VC-A)中采用协议:

Adopt the protocol in your recieving class (here, VC-A):

class ViewControllerA: UIViewController, AlertViewProtocol {
...
...
}

在VC-A中实现委托方法:

Implement the delegate method in VC-A:

func alertView(View: UIAlertView!, clickedButtonAtIndex buttonIndex: Int) {
    // Do your stuff
    // when you click on the designated button in your VC-B, this method will be invoked
}

在要实例化VC-B对象的VC-A中设置委托.就我而言，这就像:

Set the delegate in VC-A where you are instantiating the VC-B object. In my case this is like:

在这里，vcb?.delegate = self非常重要.如果忘记使用self设置对象的委托属性，则委托过程将无法进行.

Here, vcb?.delegate = self is very important. If you forget to set the delegate property of the object with self the delegation process won't work.

    @IBAction func showVCB(sender: AnyObject) {
        let vcb: ViewControllerB? = self.storyboard?.instantiateViewControllerWithIdentifier("viewcontrollerB") as? ViewControllerB
        vcb?.delegate = self
        self.presentViewController(vcb!, animated: true, completion: nil)
    }

希望，这可以帮助您了解代表如何工作的过程.

Hope, this helps you for understanding the process of how the delegates work.

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