前言
iOS讲多线程的例子很多，我就不再多说了，我主要是用代码去测试，下面是我的代码。
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// [self tongbuchuanxing];
// [self tongbubingxing];
// [self yibuchuanxing];
// [self yibubingxing];
// [self groupTest];
// [self yibuchuangxingshunxuzhixing];
[self yibubingxingshunxuzhixing];
}
- (void)tongbuchuanxing{
// 创建队列
dispatch_queue_t queue = dispatch_queue_create("zq.test.com", DISPATCH_QUEUE_SERIAL);
//主线程执行
dispatch_sync(queue, ^{
NSLog(@"1");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"2");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"3");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//直接获取主线程队列,崩溃
//个人理解应该主队列正在在执行任务的时候，然后给主队列又添加了新的任务，导致崩溃
//说明主队列不能同时进行访问
// NSLog(@"%@",dispatch_get_main_queue());
// dispatch_sync(dispatch_get_main_queue(), ^{
// NSLog(@"4");
// NSLog(@"线程：%@",[NSThread currentThread]);
// });
//开辟新线程去执行同步任务
[NSThread detachNewThreadWithBlock:^{
dispatch_sync(dispatch_get_global_queue(0, 0), ^{
NSLog(@"5");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_sync(dispatch_get_global_queue(0, 0), ^{
NSLog(@"6");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//这里在其他线程去获取主线，在主线程中添加任务，说明刚才我的猜想是正确的
dispatch_sync(dispatch_get_main_queue(), ^{
NSLog(@"7");
NSLog(@"线程：%@",[NSThread currentThread]);
});
}];
}
- (void)tongbubingxing{
//获取全局队列（全局队列是一个并行队列）
dispatch_sync(dispatch_get_global_queue(0, 0), ^{
NSLog(@"1");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_sync(dispatch_get_global_queue(0, 0), ^{
NSLog(@"2");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//创建一个并行队列
dispatch_queue_t queue = dispatch_queue_create("zq.test.com", DISPATCH_QUEUE_CONCURRENT);
dispatch_sync(queue, ^{
NSLog(@"3");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"4");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//由此可知，在同步中无论是串行队列还是并行队列都在主线程中执行
}
- (void)yibuchuanxing{
//1. 异步会开辟新线程么？
//2. 主队列是一个串行队列么？是的
dispatch_queue_t queue = dispatch_queue_create("zq.test.com", DISPATCH_QUEUE_SERIAL);
dispatch_async(queue, ^{
NSLog(@"1");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"2");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"3");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"4");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//结论 异步会开辟新线程去执行任务
//到主线程中去执行了
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"5");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"6");
NSLog(@"线程：%@",[NSThread currentThread]);
});
}
- (void)yibubingxing{
dispatch_async(dispatch_get_global_queue(0, 0), ^{
NSLog(@"1");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_async(dispatch_get_global_queue(0, 0), ^{
NSLog(@"2");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//这里的线程是主线程
// dispatch_barrier_sync(dispatch_get_global_queue(0, 0), ^{
// NSLog(@"围栏");
// NSLog(@"线程：%@",[NSThread currentThread]);
// });
dispatch_barrier_async(dispatch_get_global_queue(0, 0), ^{
NSLog(@"围栏");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//前面的执行完成后才能执行后面，那可以添加多个么？ 不能添加多个 只能隔断一次
//这里的线程是线程
dispatch_barrier_async(dispatch_get_global_queue(0, 0), ^{
NSLog(@"围栏");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_async(dispatch_get_global_queue(0, 0), ^{
NSLog(@"4");
NSLog(@"线程：%@",[NSThread currentThread]);
});
//异步并且得到的顺序就有点乱了，而且 每次都会开辟一个线程
//1. 如何让他变得有序起来
}
- (void)groupTest{
//主要作用就是通知任务完成了 该做些什么了
dispatch_queue_t globalQueue = dispatch_get_global_queue(0, 0);
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, globalQueue, ^{
NSLog(@"1");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_group_async(group, globalQueue, ^{
NSLog(@"2");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_group_async(group, globalQueue, ^{
NSLog(@"3");
NSLog(@"线程：%@",[NSThread currentThread]);
});
dispatch_group_notify(group, globalQueue, ^{
NSLog(@"任务全部完成");
});
}
- (void)yibuchuangxingshunxuzhixing{
//异步串行队列，结果是按顺序执行的 开辟了一个线程
dispatch_queue_t queue = dispatch_queue_create("zq.test.com", NULL);
for (int i = 0; i <6; i++) {
dispatch_async(queue, ^{
NSLog(@"%d",i);
NSLog(@"线程：%@",[NSThread currentThread]);
});
}
}
- (void)yibubingxingshunxuzhixing{
// NSLock *lock = [NSLock new];
// for (int i = 0; i <6; i++) {
// dispatch_async(dispatch_get_global_queue(0, 0), ^{
// // 神奇的事情发生了 已经是顺序执行了
// [lock lock];
// NSLog(@"%d",i);
// NSLog(@"线程：%@",[NSThread currentThread]);
// [lock unlock];
// });
//
// }
//如果网络请求本身就是异步并发的呢,我们想要的结果顺序
//1.信号量 可以解决
dispatch_semaphore_t xinhaoliang = dispatch_semaphore_create(0);
for (int i = 0; i <10; i++) {
dispatch_semaphore_signal(xinhaoliang);
dispatch_async(dispatch_get_global_queue(0, 0), ^{
//这里也相当于加锁，不明白的话自行百度下
@synchronized(self){
dispatch_semaphore_wait(xinhaoliang, DISPATCH_TIME_FOREVER);
NSLog(@"%d",i);
NSLog(@"线程：%@",[NSThread currentThread]);
}
});
}
}
@end
写在后面
其中的代码可以自己去测试，我注释的也是我做测试用的。代码中我已经写了一些注释，不明白的地方欢迎留言。
网友评论