CABasicAnimation保持恒定速度

Question

我正在尝试用CABasicAnimation创建一个简单的动画，它将始终保持恒定的速度，即使动画必须行进的距离永远不会相同。到目前为止，这是我的代码，它正在滚动一个标签，它的大小总是变化的，但还不能保持恒定的速度。非常感谢您的帮助。

CABasicAnimation *theAnimation;
theAnimation = [CABasicAnimation animationWithKeyPath:@"transform.translation.x"];
theAnimation.speed = 1.0f;

NSNumber *fromValue = [NSNumber numberWithFloat:self.mainLabel.frame.origin.x];
NSNumber *toValue = [NSNumber numberWithFloat:-self.mainLabel.frame.size.width - self.view.frame.size.height];
theAnimation.fromValue = fromValue;
theAnimation.toValue = toValue;
//theAnimation.duration = toValue.floatValue - fromValue.floatValue;//Not right.
theAnimation.repeatCount = 999;
theAnimation.autoreverses = NO;
[mainLabel.layer addAnimation:theAnimation forKey:@"animateLayer"];

Answer 1

你有没有尝试添加：

 theAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];

在以下示例中

 theAnimation.speed = 1.0f;   

此函数用于设置动画的线性速度。