ios - 执行选择器 : didn't work properly when using dispatch_async and global_queue

Question

我想问一下performSelector:方法需要自己的runloop定时器才能正常工作有什么潜在的原因，因为如果我不专门为他设置一个runloop，他就会辞职!

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{

    NSLog(@"touchesBegan --- %@", [NSThread currentThread]);

    dispatch_async((dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)), ^{
        [self performSelector:@selector(test) withObject:nil afterDelay:2.0];

/**
*  uncomment this line to make it work
*/
       // [[NSRunLoop currentRunLoop] run];

    });

}

-(void)test
{
    NSLog(@"test --- %@", [NSThread currentThread]);
}

Answer 1

我认为您必须需要在 dispatch_async( dispatch_get_main_queue(), ^{}); 中调用您的选择器。请看下面的代码。

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{

NSLog(@"touchesBegan --- %@", [NSThread currentThread]);

    dispatch_async((dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)), ^{
        dispatch_async( dispatch_get_main_queue(), ^{ //ADDED THIS LINE
            [self performSelector:@selector(test) withObject:nil afterDelay:2.0];
            //[[NSRunLoop currentRunLoop] run];
        });//ADDED THIS LINE
    });
}