如何在CABasicAnimation中加速/减慢按钮的旋转速度

Question

我希望我的星球在靠近太阳时加速它的运动，当它离太阳更远时减速......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 。 查看预定义的定时功能 。 您可以将其中一个分配给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：

迅速：

rotationAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)

Objective-C的：

rotationAnimation.timingFunction = [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionEaseInEaseOut];