CATransition转场动画

转场动画相对来说比较简单，属性如下：

/* The name of the transition. Current legal transition types include

* `fade', `moveIn', `push' and `reveal'. Defaults to `fade'. */

//转场动画的名字，当前类型包括`fade', `moveIn', `push' and `reveal'四种。译为：交叉淡化过渡;新视图移到旧视图上面;新视图把旧视图推出去;将旧视图移开,显示下面的新视图

//在动画中间，我们可以加入颜色，形状，位置的变化等。

@property(copy) NSString *type;

//* An optional subtype for the transition. E.g. used to specify the

* transition direction for motion-based transitions, in which case

* the legal values are `fromLeft', `fromRight', `fromTop' and

* `fromBottom'. */

//主要是指明运动的方向。

@property(nullable, copy) NSString *subtype;

//startProgress和endProgress指动画过渡的开始和结束位置。

@property float startProgress;

@property float endProgress;

/* An optional filter object implementing the transition. When set the

* `type' and `subtype' properties are ignored. The filter must

* implement `inputImage', `inputTargetImage' and `inputTime' input

* keys, and the `outputImage' output key. Optionally it may support

* the `inputExtent' key, which will be set to a rectangle describing

* the region in which the transition should run. Defaults to nil. */

//即它实现了转场动画的自定义，设置了它之后，上边设置的type和subtype就无效了。

@property(nullable, strong) id filter;

注意：经过多次验证，转场动画不能与放在动画组中与其他动画一起使用。转场动画主要用于转场使用。