《iOS多线程简介》中提到：GCD中有2个核心概念：1、任务（执行什么操作）2、队列（用来存放任务）
那么多线程GCD的基本使用有哪些呢？
可以分以下多种情况：
1、异步函数 + 并发队列
/**
* 异步函数 + 并发队列：可以同时开启多条线程
*/
- (void)asyncConcurrent
{
// 1.创建一个并发队列
// dispatch_queue_create(const char *label, dispatch_queue_attr_t attr);
// label : 相当于队列的名字
// dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_CONCURRENT); // 1.获得全局的并发队列
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, ); // 2.将任务加入队列
dispatch_async(queue, ^{
for (NSInteger i = ; i<; i++) {
NSLog(@"this is first %@",[NSThread currentThread]);
}
});
dispatch_async(queue, ^{
for (NSInteger i = ; i<; i++) {
NSLog(@"this is second %@",[NSThread currentThread]);
}
}); dispatch_async(queue, ^{
for (NSInteger i = ; i<; i++) {
NSLog(@"this is third %@",[NSThread currentThread]);
}
}); }
2、同步函数 + 并发队列
/**
* 同步函数 + 并发队列：不会开启新的线程
*/ - (void)syncConcurrent
{
// 1.获得全局的并发队列
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, ); // 2.将任务加入队列
dispatch_sync(queue, ^{
NSLog(@"this is first %@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"this is second %@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"this is third %@",[NSThread currentThread]);
}); }
3、异步函数 + 串行队列
/**
* 异步函数 + 串行队列：会开启新的线程，但是任务是串行的，执行完一个任务，再执行下一个任务
*/
- (void)asyncSerial
{
// 1.创建串行队列
dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_SERIAL);
// dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", NULL); // 2.将任务加入队列
dispatch_async(queue, ^{
NSLog(@"this is first %@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"this is second %@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"this is third %@",[NSThread currentThread]);
});
}
4、同步函数 + 串行队列
/**
* 同步函数 + 串行队列：不会开启新的线程，在当前线程执行任务。任务是串行的，执行完一个任务，再执行下一个任务
*/
- (void)syncSerial
{
// 1.创建串行队列
dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_SERIAL); // 2.将任务加入队列
dispatch_sync(queue, ^{
NSLog(@"this is first %@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"this is second %@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"this is third %@",[NSThread currentThread]);
});
}
5、异步函数 + 主队列
// * 异步函数 + 主队列：只在主线程中执行任务 - (void)asyncMain
{
// 1.获得主队列
dispatch_queue_t queue = dispatch_get_main_queue();
// 2.将任务加入队列
dispatch_async(queue, ^{
NSLog(@"this is first %@",[NSThread currentThread]);
NSLog(@"this is second %@",[NSThread currentThread]);
NSLog(@"this is third %@",[NSThread currentThread]);
});
}
6、同步函数 + 主队列
// * 同步函数 + 主队列：
- (void)syncMain
{
NSLog(@"begin"); // 1.获得主队列
dispatch_queue_t queue = dispatch_get_main_queue();
// 2.将任务加入队列
dispatch_sync(queue, ^{
NSLog(@"this is %@",[NSThread currentThread]); });
NSLog(@"end");
}
造成“相互等待的死锁”