沿着圆形路径的UIView动画？

Question

我需要让我的小家伙（在UIIamgeView中）向前跳，它必须看起来很自然。我想知道有没有办法用CoreAnimation（beginAnimation / commitAnimation）做到这一点？

我可以通过在空中设置一个点，但运动看起来不自然：P

Answer 1

阅读Brad Larson的帖子，我最终得到了一个很好的功能，让我的图像跟随一个圆圈。

您需要导入QuartzCore框架：#import

以下是代码：

// Set up path movement
CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
pathAnimation.calculationMode = kCAAnimationPaced;
pathAnimation.fillMode = kCAFillModeForwards;
pathAnimation.removedOnCompletion = NO;
pathAnimation.repeatCount = INFINITY;
//pathAnimation.rotationMode = @"auto";
pathAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
pathAnimation.duration = 5.0;

// Create a circle path
CGMutablePathRef curvedPath = CGPathCreateMutable();
CGRect circleContainer = CGRectMake(0, 0, 400, 400); // create a circle from this square, it could be the frame of an UIView
CGPathAddEllipseInRect(curvedPath, NULL, circleContainer);

pathAnimation.path = curvedPath;
CGPathRelease(curvedPath);

[self.imageView.layer addAnimation:pathAnimation forKey:@"myCircleAnimation"];

Answer 2

创建CAKeyframeAnimation并为其path属性分配CGPath。

Answer 3

为了跟进Ole的回答，my answer到this question提供了使用CAKeyframeAnimation执行此类曲面动画的代码。