如何在 CABasicAnimation 中加速/减慢按钮的旋转

Question

我希望我的星球在靠近太阳时加速运动，在远离太阳时减速。请帮助我！谢谢

CABasicAnimation* rotationAnimation;

rotationAnimation=[CABasicAnimationanimationWithKeyPath:@"transform.rotation.z"];
rotationAnimation.toValue = [NSNumber numberWithFloat: -M_PI * 2.0 /* full rotation*/ * 1/period ];//multiply more to add speed
rotationAnimation.duration = 15;
rotationAnimation.cumulative = YES;
rotationAnimation.repeatCount =  HUGE_VALF;
[planet.layer addAnimation:rotationAnimation forKey:@"orbit"];

Answer 1

您想使用CAMediaTimingFunction。查看pre-defined timing functions。您可以将其中之一分配给rotationAnimation.timingFunction。听起来你想要kCAMediaTimingFunctionEaseInEaseOut。我假设行星的起点远离太阳。在代码中，它看起来像这样：

斯威夫特：

rotationAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)

目标-C：

rotationAnimation.timingFunction = [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionEaseInEaseOut];