GCD相当好用，但用不好就会死锁,始终要记着这样一句秘籍：
不要在串行队列放dispatch_sync、dispatch_apply
下面看几个例子
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// 防死锁秘籍：不要在串行队列放dispatch_sync、dispatch_apply // 死锁 主线程调用dispatch_apply dispatch_async(dispatch_get_main_queue(), ^{ dispatch_apply(5, dispatch_get_main_queue(), ^(size_t i) { NSLog(@"%ld",i); NSLog(@"%d",55); }); }); NSLog(@"%d",999); //死锁 主线程调用dispatch_apply dispatch_apply(5, dispatch_get_main_queue(), ^(size_t i) { NSLog(@"%ld",i); NSLog(@"%d",777); }); //不死锁 dispatch_queue_t queue= dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_apply(5, queue, ^(size_t i) { NSLog(@"%ld",i); NSLog(@"%d",66); }); NSLog(@"%d",88); //不死锁 dispatch_async(queue, ^{ dispatch_apply(5, dispatch_get_main_queue(), ^(size_t i) { NSLog(@"%ld",i); }); });// //不死锁 dispatch_async(queue,^{ dispatch_sync(dispatch_get_main_queue(), ^{ NSLog(@"test"); }); }); //死锁 dispatch_sync(queue,^{ dispatch_sync(dispatch_get_main_queue(), ^{ NSLog(@"test"); }); }); |