在Swift / Objective

本文介绍了在Swift / Objective-C中实现下一个线程解决方案的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我开始学习 iOS 的编程，我想了解如何在 Swift中使用线程实现下一个 Java 函数，以及 Objective-C （在我的应用中，我也有一些使用此语言的代码）

I started to learn programming for iOS and I want to find out how to implement next Java functions with threads in Swift, and also in Objective-C (in my app I have some code using this language too)

Java线程（用于Android应用程序）

1）等待两个或多个线程完成

1) Wait for two or more threads to finished

final CountDownLatch latch = new CountDownLatch(2); // start thread #1 new Thread(new Runnable() { @Override public void run() { // do some work latch.countDown(); } }).start(); // start thread #2 new Thread(new Runnable() { @Override public void run() { // do some work latch.countDown(); } }).start(); // wait for 2 threads to end (finish) try { latch.await(); } catch (InterruptedException e) { // } // two threads are finished // do other work

2）仅当前一个线程此时完成或任何线程尚未启动时才启动新线程（ mThread == null ）

2) Start new thread only if previous one was finished at this time or any thread wasn't started yet (mThread == null)

private Thread mThread = null; // class field

。

// check if thread has completed execution if ((mThread != null && mThread.getState() == Thread.State.TERMINATED) || mThread == null) { mThread = new Thread(new Runnable() { @Override public void run() { // do some work } }); mThread.start(); }

推荐答案

我对第一个的回答（ 1）解决方案（等待所有线程完成执行）：

my answer for the first (1) solution (wait until all threads finish its execution):

dispatch_group_t group = dispatch_group_create(); dispatch_group_async(group,dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^ { // block1 NSLog(@"Task Block1"); [NSThread sleepForTimeInterval:6.0]; NSLog(@"Task Block1 End"); }); dispatch_group_async(group,dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^ { // block2 NSLog(@"Task Block2"); [NSThread sleepForTimeInterval:5.0]; NSLog(@"Task Block2 End"); }); dispatch_group_wait(group, DISPATCH_TIME_FOREVER); // blocks current thread

第二个解决方案（2）

我没有找到像 isRunning 这样的GCD方法，所以我只使用布尔变量

I didn't find for GCD method like isRunning, so I just use Boolean variable

在启动异步任务集变量isRunning为true之前 ... ... 当异步任务完成时我们可以使用下一个回调：

before starting async task set variable isRunning to true ... ... when async task is finished we can use next callback:

dispatch_group_notify(_signInitThread, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^ { isRunning = false; });