Xcode:如何在CATransaction中进行线性动画

Question

我的交易开始很慢，很快，然后就慢了。我需要线速度。

我找到了UIViewAnimationOptionCurveLinear，但找不到[CATransaction begin]的例子

这是我的代码：

[ CATransaction begin ]; 
    if( graph_animation_enable )
        [CATransaction setAnimationDuration: graph_animation_seconds ];
    else
        [CATransaction setAnimationDuration: 0 ];

    //[CATransaction setValue : ( id ) kCFBooleanTrue forKey : kCATransactionDisableActions]; 
    graph_CALayer.frame = CGRectMake( left_x, top_y, width, height );
    graph_CALayer.backgroundColor = bar_background_color.CGColor;

    CAMediaTimingFunction *linearTiming = 
      [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionLinear];
    [CATransaction setAnimationTimingFunction: linearTiming];

[CATransaction commit];

我试过答案，但仍然是非线性的。动画开始，但随后慢下来。

Answer 1

使用CATransaction setAnimationTimingFunction和kCAMediaTimingFunctionLinear的定时值

代码将如下所示：

CAMediaTimingFunction *linearTiming = 
  [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionLinear];
[CATransaction setAnimationTimingFunction: linearTiming]

Answer 2

使用Swift 5，CATransaction有一个名为setAnimationTimingFunction(_:)的方法。setAnimationTimingFunction(_:)有以下声明：

class func setAnimationTimingFunction(_ function: CAMediaTimingFunction?)

设置用于此事务组中所有动画的计时函数。..。这是一种方便的方法，可以为CAMediaTimingFunction键的value(forKey:)值设置kCATransactionAnimationTimingFunction。

因此，您可以使用以下代码片段之一为CATransaction设置线性动画

CATransaction.begin()
CATransaction.setAnimationTimingFunction(CAMediaTimingFunction(name: CAMediaTimingFunctionName.linear))
/* ... */
CATransaction.commit()

CATransaction.begin()
CATransaction.setValue(CAMediaTimingFunction(name: CAMediaTimingFunctionName.linear), forKey: kCATransactionAnimationTimingFunction)
/* ... */
CATransaction.commit()