从viewDidLoad调用方法时,CABasicAnimation不起作用

Question

我有一个imageView添加到一个视图,它呈现为modalViewController,风格水平翻转.我添加了以下代码来动画imageView.

- (void)animateTheImageview:(UIImageView*) imageViewToAnimate{
    
    CABasicAnimation *fadeAnimation;
    fadeAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
    fadeAnimation.duration = 1.5;
    fadeAnimation.repeatCount = INFINITY;
    fadeAnimation.autoreverses = NO;
    fadeAnimation.fromValue = [NSNumber numberWithFloat:1.0];
    fadeAnimation.toValue = [NSNumber numberWithFloat:0.5];
    fadeAnimation.removedOnCompletion = YES;
    fadeAnimation.fillMode = kCAFillModeForwards;
    [imageViewToAnimate.layer addAnimation:fadeAnimation forKey:@"animateOpacity"]; 
}


- (void)switchOnorOff
 {
    
    if (onOffSwitch.on)
    {
        
        self.lightImage.image = [UIImage imageNamed:@"CFLGlow.jpg"];
        [self animateTheImageview:self.lightImage];
    }
    else
    {
        
        self.lightImage.image = [UIImage imageNamed:@"CFL-BULB.jpg"];
        [self.lightImage.layer removeAllAnimations];
    }
}

我从以下方法中调用此方法viewDidLoad:

- (void)viewDidLoad
   {
      [self switchOnorOff];
   }

我的问题是上面的代码没有为imageView设置动画.

但是当我尝试下面的代码时,它可以工作:

[self performSelectorOnMainThread:@selector(animateTheImageview:) withObject:self.lightImage waitUntilDone:YES];

我的问题是为什么会出现这个问题？之间有什么区别,

[self performSelectorOnMainThread:@selector(animateTheImageview:) withObject:self.lightImage waitUntilDone:YES];

和

[self animateTheImageview:self.lightImage];

Answer 1

您不应该在viewDidLoad中执行任何动画,并且还要在其中调用[super viewDidLoad],因为您只是覆盖它.尝试在viewWillAppear或viewDidAppear上显示它.

然后,根据NSObject Reference,performSelectorOnMainThread:withObject:waitUntilDone:

在主线程的运行循环上对消息进行排队

因此队列中的其他消息可以在执行动画之前完成.

希望这可以帮助