ios - 响应选择器但抛出错误

Question

- (void)TargetHit:(int)target{

    void (^threadBlock)(void) = ^{
        NSLog(@"respond to selector %d", [self respondsToSelector:@selector(changeImageOfTarget:)]);

        [[NSOperationQueue mainQueue] performSelectorOnMainThread:@selector(changeImageOfTarget:) withObject:[NSNumber numberWithInt:target] waitUntilDone:YES];
        [NSThread sleepForTimeInterval:1.0]; 
        [[NSOperationQueue mainQueue] performSelectorOnMainThread:@selector(changeImageOfTarget:) withObject:[NSNumber numberWithInt:target] waitUntilDone:YES];
    };

    dispatch_async(dispatch_queue_create(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), threadBlock);
}

我能理解为什么我的代码返回 YES 来响应选择器，但是当我尝试执行它时，我收到一条错误消息并且应用程序崩溃了。

[NSOperationQueue changeImageOfTarget:]: unrecognized selector sent to instance 0x6a39810'

对于

也是一样的

 [[NSThread currentThread] performSelectorOnMainThread:@selector(changeImageOfTarget:) withObject:[NSNumber numberWithInt:target] waitUntilDone:YES];

我怎样才能在主线程上执行一个方法或@selector？

Answer 1

self 可能会响应选择器。问题是 [NSOperationQueue mainQueue] 没有。

How am I able to perform a method or @selector on the main thread?

只需在您希望执行操作的对象上调用它:

[self performSelectorOnMainThread:@selector(changeImageOfTarget:) withObject:[NSNumber numberWithInt:target] waitUntilDone:YES];