/*
方法名决定是否开启新线程(async,sync)，队列类型(全局队列，串行队列)决定开启多少条线程
1.快速线程调用
*开启后台线程执行任务
[self performSelectorInBackground:@selector(test) withObject:nil];
*回到主线程执行任务
[self performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];
2.GCD ： 依赖队列执行
1> 队列类型
* 全局队列
* 所有添加到全局队列中的任务都是并发执行（同时执行，可能会开启多个线程）
* dispatch_get_global_queue
* 串行队列
* 所有添加到串行队列中的任务都是按顺序执行（开一条线程）
* dispatch_queue_create("myqueue", 0);
* 主队列
* 所有添加到主队列中的任务都是在主线程中执行的(跟方法名没有关系)
* dispatch_get_main_queue
2> 同步还是异步，取决于方法名(不影响主队列，影响全局队列、串行队列)
* 同步：dispatch_sync,在当前线程执行任务，不会开启新的线程
* 异步：dispatch_async，在其他线程执行任务，会开启新的线程
3.NSOperation\NSOperationQueue
1> 使用步骤
* 创建NSOperation
* 添加NSOperation到NSOperationQueue
2> 优点
* 更加面向对象
* 可以控制最大并发数 maxConcurrentOperationCount
* 添加任务（Operation）之间的依赖 addDependency
*/
#import "XMQViewController.h"
@interface XMQViewController ()
{
NSOperationQueue *_queue;
}
@end
@implementation XMQViewController
- (void)viewDidLoad
{
[super viewDidLoad];
_queue = [[NSOperationQueue alloc] init];
// 控制最大并发数，最多同时执行3条线程
_queue.maxConcurrentOperationCount = 3;
// 回到主线程
// [self test];
// 线程监听
// [self gcd_group];
// GCD线程依赖
// [self gcd_barrier];
// 循环执行
[self gcd_apply];
// 全局队列
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
// 串行队列
// dispatch_queue_t queue2 = dispatch_queue_create("myqueue", 0);
dispatch_async(queue, ^{ // 耗时操作
NSLog(@"这是一个异步线程---%@", [NSThread currentThread]);
});
}
- (IBAction)click
{
NSOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"operation---%@", [NSThread currentThread]);
}];
NSOperation *operation2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"operation2---%@", [NSThread currentThread]);
}];
// 该方法默认在主线程执行
// [operation start];
// 加入队列会在异步线程执行
[_queue addOperation:operation];
[_queue addOperation:operation2];
// 设置线程依赖 (operation2依赖于operation，operation执行完以后，才能执行operation2)
[operation addDependency:operation2];
}
// 延时执行某条线程
- (IBAction)click2
{
// 全局队列
// dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
// 串行队列
dispatch_queue_t queue2 = dispatch_queue_create("myqueue", 0);
double delayInSeconds = 5.0;
dispatch_time_t delayInNanoSeconds =dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(delayInNanoSeconds, queue2, ^{
NSLog(@"延迟执行");
});
}
// dispatch_group_async(异步方法)可以实现监听一组任务是否完成，完成后得到通知执行其他的操作(比如通知用户下载完成,显示UI等)
- (void)gcd_group
{
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, queue, ^{
[NSThread sleepForTimeInterval:1];
NSLog(@"group1");
});
dispatch_group_async(group, queue, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"group2");
});
dispatch_group_async(group, queue, ^{
[NSThread sleepForTimeInterval:3];
NSLog(@"group3");
});
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
NSLog(@"updateUI");
});
}
// dispatch_barrier_async 是在前面的任务执行结束后才执行，而且后面的任务必须等它执行完成之后才会执行
- (void)gcd_barrier
{
dispatch_queue_t queue = dispatch_queue_create("myqueue", DISPATCH_QUEUE_CONCURRENT);
dispatch_async(queue, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"dispatch_async1");
});
dispatch_async(queue, ^{
[NSThread sleepForTimeInterval:4];
NSLog(@"dispatch_async2");
});
dispatch_barrier_async(queue, ^{
NSLog(@"dispatch_barrier_async");
[NSThread sleepForTimeInterval:4];
});
dispatch_async(queue, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"dispatch_async3");
});
}
// dispatch_apply 执行某个代码片段N次
- (void)gcd_apply
{
dispatch_queue_t queue = dispatch_queue_create("myqueue", DISPATCH_QUEUE_PRIORITY_DEFAULT);
dispatch_apply(10, queue, ^(size_t index) {
NSLog(@"循环执行10次");
});
}
// 回到主线程
- (void)test
{
UIImage *image = nil;
[self performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"更新UI界面---%@", [NSThread currentThread]);
});
}
@end
原文地址：http://www.cnblogs.com/xmqios/p/gcd_NSThread_NSOperation_NSOperationQueue.html
