总结:同步(不管是串行还是并行)----不开辟子线程
异步(不管是串行还是并行)----开辟子线程
GCD：
dispatch queue
主线程的main queue
并行队列 global dispatch queue
串行队列serial queues
一般用于按顺序同步访问
#pragma mark - 加载多线程
- (void) _loadMutil
{
//GCD基于C语言
//1.主对列:(串行队列)
dispatch_queue_t mainQueue=dispatch_get_main_queue();
//2.全局并行队列
dispatch_queue_t concu=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,
0);
//3.创建串行队列
dispatch_queue_t queueSerial=dispatch_queue_create("jrqueue1",
DISPATCH_QUEUE_SERIAL);
//4.创建并行队列
dispatch_queue_t queueConcu=dispatch_queue_create("jrqueue2",
DISPATCH_QUEUE_CONCURRENT);
//同步执行+串行队列
/*
dispatch_sync(queueSerial, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"同步串行队列1-----%@",[NSThread currentThread]);
});
dispatch_sync(queueSerial, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"同步串行队列2-----%@",[NSThread currentThread]);
});
*/
//同步执行+并行队列
/*
dispatch_sync(queueConcu, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"同步并行队列1-----%@",[NSThread currentThread]);
});
dispatch_sync(queueConcu, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"同步并行队列2-----%@",[NSThread currentThread]);
});
*/
//异步执行+串行队列-----开启一个子线程，且顺序执行
/*
dispatch_async(queueSerial, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"异步串行队列1-----%@",[NSThread currentThread]);
});
dispatch_async(queueSerial, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"异步串行队列2-----%@",[NSThread currentThread]);
});
dispatch_async(queueSerial, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"异步串行队列3-----%@",[NSThread currentThread]);
});
*/
//异步执行+并行队列----开启多个线程，且并发执行(无序)
/*
dispatch_async(queueConcu, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"异步并行队列1-----%@",[NSThread currentThread]);
});
dispatch_async(queueConcu, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"异步并行队列2-----%@",[NSThread currentThread]);
});
dispatch_async(queueConcu, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"异步并行队列3-----%@",[NSThread currentThread]);
});
*/
//主对列+同步执行-----死锁（将以下两个添加到主队列，等待前面的执行完成（loadView。loadData之类的），但是当执行到这一步时，形成死循环）
/*
dispatch_sync(mainQueue, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"同步主队列1-----%@",[NSThread currentThread]);
});
dispatch_sync(mainQueue, ^{
[NSThread sleepForTimeInterval:2];
NSLog(@"同步主队列2-----%@",[NSThread currentThread]);
});
*/
}
@end
将以上的方法，在viewDidLoad 中调用一下，看看效果如何~