ios - 如何识别特定图像在 imageview 动画期间正在动画？

Question

我正在创建一个计时器，用于播放一首歌曲 6 秒。但我希望每当我单击该按钮时，它都会识别在该特定时刻动画的特定图像。为此，我使用了 CALayer，但它是没有给出图像名称。

这是我的代码:

-(void)playSong
{
    timerButton.imageView.animationImages =[NSArray arrayWithObjects:[UIImage   imageNamed:@"Timer6.png"],[UIImage imageNamed:@"Timer5.png"],
                                                                   [UIImage imageNamed:@"Timer4.png"],[UIImage imageNamed:@"Timer3.png"],
                                                                   [UIImage imageNamed:@"Timer2.png"],[UIImage imageNamed:@"Timer1.png"],
                                                                   nil];
    timerButton.imageView.animationDuration=6.0; 
    [self.player play];
    [timerButton.imageView startAnimating];
}

- (void)handleLongPressGestures:(UILongPressGestureRecognizer *)sender
{
 if (sender.state == UIGestureRecognizerStateBegan)
 {
       CALayer *player1 = timerButton.imageView.layer;

 }
}

请帮帮我。

Answer 1

很遗憾，您无法从 UIImageView 中获取图像名称或 UIImage对象。

但是，您可以将可访问性标识符 设置为UIImage对象，在您的情况下，可能是它的文件名。
然后简单地做 someUIImageObject.accessibilityIdentifier应该返回文件名。
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例子:

UIImage *image = [UIImage imageNamed:@"someImage.png"];
[image setAccessibilityIdentifier:@"someImage"];

NSLog(@"%@",image.accessibilityIdentifier);

---

现在...您会期望 timerButton.imageView.image.accessibilityIdentifier给你图像名称，但当 UIImageView 时，这不是它的工作方式正在动画。
这一次，我们需要通过 UIImageView 访问它s animationImages数组属性。
为此，我们需要一些自定义逻辑来获取 UIImage来自这个 animationImages 的对象数组。

我们将首先记录我们开始为图像设置动画的时间，并通过一些基本的数学计算，我们可以计算出 animationImages 的索引。当前显示在 UIImageView 中的数组.
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---

答案(代码):

-(void)playSong
{
    NSMutableArray *arrImages = [[NSMutableArray alloc] init];
    for(int i = 6 ; i > 0 ; i--) {
        //Generate image file names: "Timer6.png", "Timer5.png", ..., "Timer1.png"
        NSString *strImageName = [NSString stringWithFormat:@"Timer%d.png",i];

        //create image object
        UIImage *image = [UIImage imageNamed:strImageName];
        //remember image object's filename
        [image setAccessibilityIdentifier:strImageName];

        [arrImages addObject:image];
    }

    [timerButton.imageView setAnimationImages:arrImages];
    [timerButton.imageView setAnimationDuration:6.0f];
    [timerButton.imageView setAnimationRepeatCount:0];

    [self.player play];
    [timerButton.imageView startAnimating];

    //record start time
    startDate = [NSDate date]; //declare "NSDate *startDate;" globally
}

---

- (void)handleLongPressGestures:(UILongPressGestureRecognizer *)sender
{
    if (sender.state == UIGestureRecognizerStateBegan) {
        [self checkCurrentImage];
    }
}

---

-(void)checkCurrentImage
{
    //logic to determine which image is being displayed from the animationImages array

    NSTimeInterval durationElapsed = -1 * [startDate timeIntervalSinceNow];
    NSTimeInterval durationPerFrame = timerButton.imageView.animationDuration / timerButton.imageView.animationImages.count;
    int currentIndex = (int)(durationElapsed / durationPerFrame) % timerButton.imageView.animationImages.count;

    UIImage *imageCurrent = timerButton.imageView.animationImages[currentIndex];
    NSString *strCurrentImage = imageCurrent.accessibilityIdentifier;

    NSLog(@"%@",strCurrentImage);
}