becomeFirstResponder失败

Question

我有一个简单的问题：

如何设置代码让NSObject成为第一个响应者？在我的代码中，我将此代码放入AppDelegate，但应用程序委托未能成为第一个响应者。如果我试图让另一个NSObject成为第一个响应者，那么同样发生在我身上。

//This function is called when app enters background
- (void)prepareRemoteControlEventsListener{

    //register for remote control
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

    // Set itself as the first responder
    BOOL success = [self becomeFirstResponder];
    if (success) {
        NSLog(@"APP degelgate AVManager for remote control events");
    }else{
        NSLog(@"@@@ degelgate failed to listen remote control events @@@");
    }
}
//Suppose it should enable self becoming firstResponder?
- (BOOL)canBecomeFirstResponder{
    return YES;
}