iphone - 如何创建平滑的图像动画

我有一个动画，其中一个背景图像和12个中心针图像。它运行正常，但是每次显示图像和之后显示图像时，我只希望它在图像之间平稳运行。我怎样才能做到这一点？

这是我当前的代码:

- (IBAction)startAnimation:(id)sender
{
    imgAnimation.frame = CGRectMake(0, 0, 184.5f, 172.5f);
    imgAnimation.center = CGPointMake(160, 164);
    imgAnimation.animationImages = [NSArray arrayWithObjects:
                                [UIImage imageNamed:@"pointer01.png"],
                                [UIImage imageNamed:@"pointer02.png"],
                                [UIImage imageNamed:@"pointer03.png"],
                                [UIImage imageNamed:@"pointer04.png"],
                                [UIImage imageNamed:@"pointer05.png"],
                                [UIImage imageNamed:@"pointer06.png"],
                                [UIImage imageNamed:@"pointer07.png"],
                                [UIImage imageNamed:@"pointer08.png"],
                                [UIImage imageNamed:@"pointer09.png"],
                                [UIImage imageNamed:@"pointer10.png"],
                                [UIImage imageNamed:@"pointer11.png"],
                                [UIImage imageNamed:@"pointer12.png"], nil];
    [imgAnimation setAnimationRepeatCount:5];
    [imgAnimation setAnimationDuration:4.0f];
    [imgAnimation startAnimating];

}

最佳答案

编辑:我最初建议使用UIView动画，但是它总是采用最短的路线，旋转90度而不是270度。尝试此操作，由Can I use CGAffineTransformMakeRotation to rotate a view more than 360 degrees?提供

为了获得尽可能平滑的针动画，请不要使用一系列图像。从UIImageView中的单针图像开始，其视图以背景刻度盘图像为中心。然后使用旋转变换更改UIImageView图层的transform属性。

排列好几何之后，请使用“核心动画”为在适当角度范围内变化的变换设置动画。

为了详细说明，假设imgAnimation是UIImageView:

- (IBAction)startAnimation:(id)sender
{
    // This assumes that the center of the needle image is the center of the dial.  If they aren't, it's probably simplest to resize the needle image so it is centered.
    imgAnimation.frame = CGRectMake(0, 0, 184.5f, 172.5f);
    imgAnimation.center = CGPointMake(160, 164);

    // The needle image used should show the needle pointing straight up, or some other known direction.
    imgAnimation.image = [UIImage imageNamed:@"pointer06.png"];
    // Position the needle in its position before animating.
    [imgAnimation.layer setTransform:CATransform3DMakeRotation(-M_PI*3/4, 0, 0, 1)];

    // Construct an animation moving the needle to its end position.
    // Mose of these properties should be self-explanatory.  Look up the CABasicAnimation Class Reference if not.
    CABasicAnimation *needleAnim = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    needleAnim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    needleAnim.duration = 4;
    needleAnim.repeatCount = 5;
    needleAnim.autoreverses = YES;
    // Setting fillMode means that, once the animation finishes, the needle stays in its end position.
    needleAnim.fillMode = kCAFillModeForwards;
    needleAnim.removedOnCompletion = YES;
    needleAnim.toValue = [NSNumber numberWithFloat:M_PI*3/4];

    // Add the animation to the needle's layer.
    [senderView.layer addAnimation:needleAnim forKey:nil];
}

关于iphone - 如何创建平滑的图像动画，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/10054693/