GCD:
dispatch_queue_t queue1 = dispatch_queue_create("CONCURRENT", DISPATCH_QUEUE_CONCURRENT);//并发
// 将任务添加到队列中
for (NSInteger index = 0; index < 10; index ++) {
dispatch_async(queue1, ^{//异步
NSLog(@"任务%ld 线程%@",index,[NSThread currentThread]);
});
}
打印结果：
2018-03-31 01:47:32.286672+0800 PodsTest[1301:124255] 任务7 线程<NSThread: 0x604000465400>{number = 10, name = (null)}
2018-03-31 01:47:32.286672+0800 PodsTest[1301:124217] 任务4 线程<NSThread: 0x60000007e040>{number = 7, name = (null)}
2018-03-31 01:47:32.286668+0800 PodsTest[1301:124227] 任务3 线程<NSThread: 0x6040004654c0>{number = 6, name = (null)}
2018-03-31 01:47:32.286668+0800 PodsTest[1301:124226] 任务0 线程<NSThread: 0x60c000265440>{number = 3, name = (null)}
2018-03-31 01:47:32.286686+0800 PodsTest[1301:124230] 任务1 线程<NSThread: 0x6040004653c0>{number = 4, name = (null)}
2018-03-31 01:47:32.286688+0800 PodsTest[1301:124256] 任务8 线程<NSThread: 0x60000007e140>{number = 11, name = (null)}
2018-03-31 01:47:32.286699+0800 PodsTest[1301:124254] 任务6 线程<NSThread: 0x60c000265a00>{number = 9, name = (null)}
2018-03-31 01:47:32.286709+0800 PodsTest[1301:124219] 任务2 线程<NSThread: 0x60c000265980>{number = 5, name = (null)}
2018-03-31 01:47:32.286710+0800 PodsTest[1301:124253] 任务5 线程<NSThread: 0x60000007e000>{number = 8, name = (null)}
2018-03-31 01:47:32.286728+0800 PodsTest[1301:124257] 任务9 线程<NSThread: 0x60800007b780>{number = 12, name = (null)}
NSOperation:
第一种基本用法：
NSInvocationOperation *invocationOperation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(invocaAction) object:nil];
[invocationOperation start];
- (void)invocaAction {
NSLog(@"invocation %@",[NSThread currentThread]);
}
打印结果：
2018-03-31 02:02:59.408650+0800 PodsTest[1517:148998] invocation <NSThread: 0x60c000076200>{number = 1, name = main}
第二种基本用法：
NSBlockOperation *blockOperation = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"任务1 线程%@",[NSThread currentThread]);
}];
[blockOperation addExecutionBlock:^{
NSLog(@"任务2 线程%@",[NSThread currentThread]);
}];
[blockOperation addExecutionBlock:^{
NSLog(@"任务3 线程%@",[NSThread currentThread]);
}];
[blockOperation start];
打印结果：
2018-03-31 01:59:43.584362+0800 PodsTest[1469:143515] 任务1 线程<NSThread: 0x604000064c40>{number = 1, name = main}
2018-03-31 01:59:43.584362+0800 PodsTest[1469:143555] 任务3 线程<NSThread: 0x60000006acc0>{number = 4, name = (null)}
2018-03-31 01:59:43.584364+0800 PodsTest[1469:143563] 任务2 线程<NSThread: 0x6080002785c0>{number = 3, name = (null)}
这种方法会优先把任务放到主线程中执行，而且有最大并发数，具体的最大并发数和运行环境有关，如果任务数量大于这个数，那么剩下的任务就会等待某个线程空闲下来之后再被分配到该线程，且依然是优先分配到主线程，同一个线程的block为同步执行
最简便用法：
NSOperationQueue *operationQueue = [[NSOperationQueue alloc]init];
[operationQueue addOperationWithBlock:^{
NSLog(@"任务1 线程%@",[NSThread currentThread]);
}];
[operationQueue addOperationWithBlock:^{
NSLog(@"任务2 线程%@",[NSThread currentThread]);
}];
[operationQueue addOperationWithBlock:^{
NSLog(@"任务3 线程%@",[NSThread currentThread]);
}];
[operationQueue addOperationWithBlock:^{
NSLog(@"任务4 线程%@",[NSThread currentThread]);
}];
打印结果：
2018-03-31 02:06:02.480051+0800 PodsTest[1561:154419] 任务2 线程<NSThread: 0x604000078340>{number = 6, name = (null)}
2018-03-31 02:06:02.480057+0800 PodsTest[1561:154413] 任务3 线程<NSThread: 0x60c000260800>{number = 5, name = (null)}
2018-03-31 02:06:02.480069+0800 PodsTest[1561:154420] 任务1 线程<NSThread: 0x60c0002608c0>{number = 3, name = (null)}
2018-03-31 02:06:02.480069+0800 PodsTest[1561:154409] 任务4 线程<NSThread: 0x604000078280>{number = 4, name = (null)}
这种方法最简便，而且可以添加依赖关系
[invo2 addDependency:invo1];
这样invo2一定在invo1执行完以后才会执行，添加依赖的代码一定要在addOperation之前，且不要建立循环依赖，会造成死锁
NSOperation提供cancel方法，也可以用NSOperationQueue的cancelAllOperations取消全部线程，设置NSOperationQueue的suspended属性可以暂停和继续，maxConcurrentOperationCount属性设置最大并发数
GCD是苹果公司为多核运算提供的一套纯C语言解决方案，拥有延迟操作(dispatch_after(时间，队列，任务))，一次性执行（只执行一次，dispatch_once）与调度组（group）等NSOperation不具备的功能
NSOperation是OC中基于GCD的面向对象的封装，对GCD进行了优化，使用比GCD更简单，提供了一些GCD不好实现的功能，且不用关心线程的生命周期，其设置最大并发数，队列的暂停 /取消，指定操作间的依赖关系是GCD不好实现的
