一、前言
- 每一个UIView内部都默认关联着一个CALayer对象，我们可用称这个Layer为
Root Layer（根层） - 所有的非RootLayer根层，也就是手动创建的CALayer对象，都存在着隐式动画
二、什么是隐式动画？
- 当对非RootLayer的部分属性进行修改时，默认会自动产生一些动画效果
- 而这些属性称为AnimatableProperties(可动画属性)
- 也就是说，对非根层的layer可动画属性进行修改产生的动画，就称为隐式动画
三、可动画属性 Animatable Properties
如上所述：我们可以修改可动画属性，来进行隐式动画，现在介绍可动画属性
查看CALayer头文件：查看部分可动画属性
哪些才可以称着，可动画属性呢？ -> 属性，注释中包含
Animatable的-
常见可动画属性
- bounds：用于设置CALayer的宽度和高度。修改这个属性会产生缩放动画
- backgroundColor：用于设置CALayer的背景色。修改这个属性会产生背景色的渐变动画
- position：用于设置CALayer的位置。修改这个属性会产生平移动画
- ............
// 查看部分头文件，还有其他的可动画属性不在此
/* The bounds of the layer. Defaults to CGRectZero. Animatable. */
@property CGRect bounds;
/* The position in the superlayer that the anchor point of the layer's
* bounds rect is aligned to. Defaults to the zero point. Animatable. */
@property CGPoint position;
/* The Z component of the layer's position in its superlayer. Defaults
* to zero. Animatable. */
@property CGFloat zPosition;
/* Defines the anchor point of the layer's bounds rect, as a point in
* normalized layer coordinates - '(0, 0)' is the bottom left corner of
* the bounds rect, '(1, 1)' is the top right corner. Defaults to
* '(0.5, 0.5)', i.e. the center of the bounds rect. Animatable. */
@property CGPoint anchorPoint;
/* The Z component of the layer's anchor point (i.e. reference point for
* position and transform). Defaults to zero. Animatable. */
@property CGFloat anchorPointZ;
/* A transform applied to the layer relative to the anchor point of its
* bounds rect. Defaults to the identity transform. Animatable. */
@property CATransform3D transform;
/* Convenience methods for accessing the `transform' property as an
* affine transform. */
- (CGAffineTransform)affineTransform;
- (void)setAffineTransform:(CGAffineTransform)m;
/* Unlike NSView, each Layer in the hierarchy has an implicit frame
* rectangle, a function of the `position', `bounds', `anchorPoint',
* and `transform' properties. When setting the frame the `position'
* and `bounds.size' are changed to match the given frame. */
@property CGRect frame;
/* When true the layer and its sublayers are not displayed. Defaults to
* NO. Animatable. */
@property(getter=isHidden) BOOL hidden;
四 隐式动画 实现 : CATransaction(动画事务)
- 可以通过动画事务(CATransaction)关闭默认的隐式动画效果
[CATransactionbegin];
[CATransactionsetDisableActions:YES];
self.myview.layer.position= CGPointMake(10,10);
[CATransactioncommit];
五、实例
-
实例：
隐式动画.gif- 点击屏幕，让控制器上的view视图上的一个矩形子控件，不断地进行改变：位置，颜色，与圆角
思路：其实很简单，在touchBegin:方法中 -> 就是不断修改layer的可动画属性实现的
代码实现：如下
#import "ViewController.h"
@interface ViewController ()
@property (nonatomic, weak) CALayer *greenLayer;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// 添加 一个自定义的layer到控制器的view的layer上
CALayer *layer = [CALayer layer];
_greenLayer = layer;
layer.position = CGPointMake(0, 0);
layer.bounds = CGRectMake(0, 0, 100, 100);
layer.anchorPoint = CGPointMake(0, 0);
layer.backgroundColor = [UIColor greenColor].CGColor;
[self.view.layer addSublayer:layer];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// 开启事务
[CATransaction begin];
// [CATransaction setDisableActions:YES];
// [CATransaction setAnimationDuration:2];
_greenLayer.position = CGPointMake(arc4random_uniform(250), arc4random_uniform(300));
_greenLayer.backgroundColor = [self randomColor].CGColor;
_greenLayer.cornerRadius = arc4random_uniform(50);
_greenLayer.borderColor = [self randomColor].CGColor;
_greenLayer.borderWidth = arc4random_uniform(5);
// 提交事务
[CATransaction commit];
}
/**
* 返回 随机色
*/
- (UIColor *)randomColor
{
CGFloat r = arc4random_uniform(256) / 255.0;
CGFloat g = arc4random_uniform(256) / 255.0;
CGFloat b = arc4random_uniform(256) / 255.0;
return [UIColor colorWithRed:r green:g blue:b alpha:1];
}
@end
```
