使用 UIAlertController 阻塞循环

Question

我们有没有办法阻止 for 循环？

我在其中有一个循环，它通过对话框询问用户。我希望它在用户按下确定或取消后暂停循环。

可能吗？

因为循环 alertController 看起来真的很难看，尤其是当你有很多循环时。

for request in friendRequests
{
    let alertController = UIAlertController(title: "Friend Request", message: "Would you like to accept this friend request?", preferredStyle: UIAlertControllerStyle.Alert);
    let cancelAction: UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Cancel, handler: nil);
    let confirmAction: UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil);

    alertController.addAction(cancelAction);
    alertController.addAction(confirmAction);

    //How do we block or wait until user press a button??  
    self.navigationController.presentViewController(alertController);
}

有什么想法吗？谢谢

Answer 1

不是创建循环，而是实现一个在用户决定后调用自身的逻辑方法。

更改方法实现，例如：

func showAlert(var requestIndex : Int)
{
    if (requestIndex < friendRequests.count)
    {
        var request = friendRequests[requestIndex]
        requestIndex++
        let alertController = UIAlertController(title: "Friend Request", message: "Would you like to accept this friend request?", preferredStyle: UIAlertControllerStyle.Alert);
        let cancelAction: UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Cancel, handler:{ action in
            showAlert(requestIndex)
        });
        let confirmAction: UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: { action in
            showAlert(requestIndex)
        });

        alertController.addAction(cancelAction);
        alertController.addAction(confirmAction);

        //How do we block or wait until user press a button??
        self.navigationController.presentViewController(alertController);
    }
}

最初调用方法如下：

showAlert(0);

Answer 2

使用递归函数而不是循环

例子

var name:[String] = ["abcd","efgh","ijkl","mnop","qrst","uvwx"]
self.friendReuqest(name, index: 0)

func friendReuqest(name:[String],index:Int)
{
    if index < name.count
    {
        let alertController = UIAlertController(title: name[index], message: "Would you like to accept this friend request?", preferredStyle: UIAlertControllerStyle.Alert)

        let cancelAction: UIAlertAction = UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.Cancel){ (action: UIAlertAction!) -> Void in
            // do stuff here when press cancel
        }

        let confirmAction: UIAlertAction = UIAlertAction(title: "Add", style: UIAlertActionStyle.Default) { (action: UIAlertAction!) -> Void in
            self.friendReuqest(name, index: (index + 1))
        }

        alertController.addAction(cancelAction)
        alertController.addAction(confirmAction)
        self.presentViewController(alertController, animated: true, completion: nil)
    }
}

使用 UIAlertController 阻塞循环

Blocking a Loop Using UIAlertController

objective-c

ios

swift

uialertcontroller