-(void)test{
NSLog(@"2");
}
-(void)test2{
NSLog(@"3");
}
- (void)viewDidLoad {
[super viewDidLoad];
//并发队列
dispatch_queue_t queue = dispatch_queue_create("batac.com", DISPATCH_QUEUE_CONCURRENT);
//异步处理任务
dispatch_async(queue, ^{
//异步并发队列处理任务, 会开启子线程处理任务
NSLog(@"1");
[self performSelector:@selector(test) withObject:nil afterDelay:.0];
[self performSelector:@selector(test2) withObject:nil];
NSLog(@"4");
});
}
以上内容会打印什么?
// 1 3 4
- 原因: performSelector: withObject:方法是使用了消息发送机制, 底层调用msg_send, 会被直接调用
- performSelector:@selector(test) withObject:nil afterDelay: 方法底层是使用NSTimer实现, 向当前线程的runloop添加了一个timer事件, 但是子线程的runloop需要手动启动才会运行;所以不会打印;
-(void)test{
NSLog(@"2");
}
-(void)test2{
NSLog(@"3");
}
- (void)viewDidLoad {
[super viewDidLoad];
//并发队列
dispatch_queue_t queue = dispatch_queue_create("batac.com", DISPATCH_QUEUE_CONCURRENT);
//异步处理任务
dispatch_async(queue, ^{
//异步并发队列处理任务, 会开启子线程处理任务
NSLog(@"1");
[self performSelector:@selector(test) withObject:nil afterDelay:.0];
[[NSRunLoop currentRunLoop] run];
[self performSelector:@selector(test2) withObject:nil];
NSLog(@"4");
});
}
//打印结果: 1 2 3 4