performSelector：使用 dispatch_async 和 global_queue 时无法正常工作

Question

我想问一下performSelector：方法是否需要自己的runloop计时器才能正常工作，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(), ^{});调用您的选择器dispatch_async( dispatch_get_main_queue(), ^{}); . 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
    });
}