如何在swift中取消多个线程中的一个

Well .. I'm in situation like this: I have a function that starts 3 asynchronous threads. Each thread do something wich take some time. When some thread finish first, I need it to stop the other 2, but I dont know how to do it (yet).

嗯. .我现在的情况是:我有一个启动3个异步线程的函数。每条线都需要一些时间。当一些线程先完成时，我需要它来停止另外两个线程，但是我还不知道怎么做。

My code:

我的代码:

    class SomeController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
    threads();
}

func threads(){

    let operationQueue = NSOperationQueue();

    operationQueue.addOperationWithBlock(
        {
            let thread = NSThread.currentThread();
            let threadNumber = thread.valueForKeyPath("private.seqNum").integerValue;
            NSThread.sleepForTimeInterval(30);

            println("Task #1 completed on thread #\(threadNumber)");

    })

    operationQueue.addOperationWithBlock(
        {
            let thread = NSThread.currentThread();
            let threadNumber = thread.valueForKeyPath("private.seqNum").integerValue;

            NSThread.sleepForTimeInterval(20);
            println("Task #2 completed on thread #\(threadNumber)");

    })

    operationQueue.addOperationWithBlock(
        {
            let thread = NSThread.currentThread();
            let threadNumber = thread.valueForKeyPath("private.seqNum").integerValue;

            NSThread.sleepForTimeInterval(5);
            println("Task #3 completed on thread #\(threadNumber)");
    })
}}

Any Swift help or advice will be apperciated :)

任何迅速的帮助或建议将被告知:)

2 个解决方案

#1

This isn't really a question about canceling an NSThread. Rather, it's a question of how to cancel an NSOperation. In this case, it's relatively easy to cancel all the operations since you're creating a single NSOperationQueue for the sole purpose of executing your three blocks. Just send the operationQueue a cancelAllOperations message:

这并不是关于取消NSThread的问题。而是如何取消ns操作的问题。在这种情况下，取消所有操作相对容易，因为您正在创建一个NSOperationQueue，惟一的目的是执行三个块。只需发送操作队列一个cancelAllOperations消息:

operationQueue.cancelAllOperations()

The unfortunate part is that operation canceling is really cooperative, so within the operation you have to periodically check isCancelled and terminate as required:

不幸的是，取消操作是非常合作的，因此在操作中，您必须定期检查是否被取消，并按要求终止:

var operation3:NSOperation?
operation3 = operationQueue.addOperationWithBlock {
    let thread = NSThread.currentThread()
    let threadNumber = thread.valueForKeyPath("private.seqNum").integerValue
    var timeout = 5

    while timeout-- > 0 && !operation3.isCancelled {
        NSThread.sleepForTimeInterval(1)
    }

    println("Task #3 completed on thread #\(threadNumber)")

    operationQueue.cancelAllOperations()
}

#2

If you create an operation with addOperationWithBlock, you can cancel it all you like, it has no effect. If you want to cancel an operation, I recommend not using a block, but subclassing NSOperation. The task that is getting executed must check manually when it's cancelled and finish the task; you can't do that with addOperationWithBlock.

如果您使用addOperationWithBlock创建一个操作，您可以取消它，它没有任何效果。如果您想取消操作，我建议不使用块，而是子类化NSOperation。正在执行的任务必须在取消时手动检查并完成任务;你不能用addOperationWithBlock那样做。