CALyer简单介绍和使用

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一、position和anchorPoint

1.简单介绍

CALayer有2个非常重要的属性：position和anchorPoint

@property CGPoint position;

用来设置CALayer在父层中的位置

以父层的左上角为原点(0, 0)

@property CGPoint anchorPoint;

称为“定位点”、“锚点”

决定着CALayer身上的哪个点会在position属性所指的位置

以自己的左上角为原点(0, 0)

它的x、y取值范围都是0~1，默认值为（0.5, 0.5）

二、了解一下CALayer的基本常用的属性：

    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];        button.frame = CGRectMake(100, 50, 175, 175);        [button setBackgroundImage:[UIImage imageNamed:@"06.jpg"] forState:UIControlStateNormal];        [self.view addSubview:button];        button.layer.cornerRadius = 20 ;        button.layer.borderColor = [[UIColor yellowColor]CGColor];        button.layer.borderWidth = 2 ;    //    button.clipsToBounds = YES ;    //阴影颜色    button.layer.shadowColor = [[UIColor blackColor]CGColor];        //阴影的偏移距离    button.layer.shadowOffset = CGSizeMake(20, 20);        //阴影的透明度    button.layer.shadowOpacity = 0.8 ;        //阴影    button.layer.shadowRadius = 20 ;        //是否裁剪边框之外的//    button.layer.masksToBounds = YES ;            //CALayer负责视图的渲染 UI中真正负责绘图的部分 没有用户交互，仅仅是展示视图内容，一般用来做动画    CALayer *layer = [CALayer layer];        layer.frame = CGRectMake(100, 300, 175, 175);        layer.backgroundColor = [[UIColor yellowColor]CGColor];        layer.contents = (id)[[UIImage imageNamed:@"06.jpg"]CGImage];        [self.view.layer addSublayer:layer];        layer.shadowOffset = CGSizeMake(20, 20);        layer.shadowColor = [[UIColor redColor]CGColor];        layer.shadowOpacity = 0.3 ;

三、接下来我们写个Demo来演示一下

每一个UIView内部都默认关联着一个CALayer，我们可用称这个Layer为Root Layer（根层）

所有的非Root Layer，也就是手动创建的CALayer对象，都存在着隐式动画

什么是隐式动画？

当对非Root Layer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Animatable Properties(可动画属性)

列举几个常见的Animatable Properties：

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

@interface ViewController ()@property (nonatomic,retain) CALayer *layer ;@end@implementation ViewController- (void)viewDidLoad {     [super viewDidLoad];     // Do any additional setup after loading the view, typically from a nib.     self.layer = [CALayer layer];     self.layer.bounds = CGRectMake(0, 0, 100, 100);     //设置锚点     self.layer.position = CGPointMake(187.5, 200);     //设置锚点在layer上的比例     self.layer.anchorPoint = CGPointMake(0.2, 0.2) ;     self.layer.cornerRadius = 20 ;     self.layer.borderWidth = 2 ;     self.layer.shadowOffset = CGSizeMake(20, 20);     self.layer.shadowOpacity = 0.2 ;     self.layer.doubleSided = YES ;     self.layer.borderColor = [[UIColor redColor]CGColor];     self.layer.backgroundColor = [[UIColor brownColor]CGColor];     [self.view.layer addSublayer:self.layer];}- (void)didReceiveMemoryWarning {     [super didReceiveMemoryWarning];     // Dispose of any resources that can be recreated.}#pragma mark -- 平移CALayer- (IBAction)buttonAction1:(UIButton *)sender {     //创建一个基本动画对象     CABasicAnimation *animation = [CABasicAnimation animation];     //动画的类型     //keyPath layer的某个属性     animation.keyPath = @"position";     //动画的持续时间     animation.duration = 2 ;         //toValue 就是一个临时值,通过CALayer做的动画不会改变layer属性本身的值     animation.toValue = [NSValue valueWithCGPoint:CGPointMake(100, 400)];     //如果要保留动画的最终目的，下面两个属性分都需要设置     //保持动画的最新状态     animation.fillMode = kCAFillModeBackwards ;     //设置动画完成后之后不删除     animation.removedOnCompletion = NO ;     animation.delegate = self ;     [self.layer addAnimation:animation forKey:nil];}-(void)animationDidStart:(CAAnimation *)anim{     NSLog(@"%@",NSStringFromCGRect(self.layer.bounds));}#pragma mark --实现缩放- (IBAction)buttonAction2:(UIButton *)sender {     //1.创建一个基本动画     CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"bounds"];     //2.设置动画持续时间     animation.duration = 2 ;     //3.设置动画的最终效果     animation.toValue = [NSValue valueWithCGRect:CGRectMake(0, 0, 200, 200)];     //4.使动画保留最终状态     animation.fillMode = kCAFillModeForwards ;     animation.removedOnCompletion = NO ;     //5.将动画对象付给layer     [self.layer addAnimation:animation forKey:nil];}- (IBAction)buttonAction3:(UIButton *)sender {         CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];         animation.duration = 2 ;         animation.fillMode = kCAFillModeForwards ;         animation.removedOnCompletion = NO ;         animation.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(M_PI / 3, 0, 0, 1)];     [self.layer addAnimation:animation forKey:nil];}@end

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