Core Animation核心动画

CALayer层（显示的基础）
UIView核心显示功能就是依靠CALayer实现的
如何获取一个CALayer对象
1、通过视图的.layer属性就可以获取到当前视图中layer对象
2、自己创建layer对象
普通layer (包括图片layer)
文字layer
图形layer (在layer上创建贝塞尔曲线等等)
ViewController.m

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIView *myView;
@property (weak, nonatomic) IBOutlet UIView *myView2;
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    CALayer *layer = self.myView.layer;
    layer.backgroundColor = [UIColor greenColor].CGColor;
    //边的颜色
    layer.borderColor = [UIColor blueColor].CGColor;
    //边的宽度
    layer.borderWidth = 3;
    //设置圆角半径
    layer.cornerRadius = 30;
    //需要使用阴影 一定要设置透明度 默认为0 不可见
    layer.shadowOpacity = 1;
    //设置阴影颜色
    layer.shadowColor = [UIColor blackColor].CGColor;
    //修改阴影偏移
    layer.shadowOffset = CGSizeMake(10, 10);
    //设置阴影半径
    layer.shadowRadius = 8;
    
    CALayer *layer2 = self.myView2.layer;
    layer2.backgroundColor = [UIColor greenColor].CGColor;
    //边的颜色
    layer2.borderColor = [UIColor blueColor].CGColor;
    //边的宽度
    layer2.borderWidth = 3;
    //设置圆角半径
    layer2.cornerRadius = self.myView2.frame.size.width * 0.5;
    
    
    CALayer *layer3 = self.imageView.layer;
    layer3.backgroundColor = [UIColor greenColor].CGColor;
    //如果做圆形的图片视图 必须按照层的边缘进行遮罩
    layer3.masksToBounds = YES;
    //边的颜色
    layer3.borderColor = [UIColor blueColor].CGColor;
    //边的宽度
    layer3.borderWidth = 5;
    //设置圆角半径
    layer3.cornerRadius = self.imageView.frame.size.width * 0.5;
}

ViewController.m

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIView *myView;
@property(nonatomic,strong)CALayer *myLayer;
@end

@implementation ViewController
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    //layer的某些属性自带动画，凡是属性说明上 最后一个单词是Animatable,该属性修改时自带动画
    self.myLayer.borderWidth = arc4random() % 25 + 5;
    self.myLayer.cornerRadius = arc4random() % 10 + 5;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    CALayer *myLayer = [CALayer layer];
    self.myLayer = myLayer;
    myLayer.borderWidth = 3;
    myLayer.borderColor = [UIColor redColor].CGColor;
//    myLayer.backgroundColor = [UIColor redColor].CGColor;
    //对于layer大小和位置的设定，极少用frame,通常大小利用 bounds 位置是用 positi 属性
    myLayer.bounds = CGRectMake(0, 0, 50, 50);
    //设置位置 默认 就是0，0
    myLayer.position = CGPointZero;
    //设置锚点 默认0.5，0.5及中心点
    myLayer.anchorPoint = CGPointMake(0, 0);
    //layer 最大的特点 嵌套性
    [self.myView.layer addSublayer:myLayer];
}

imageLayerViewController.m

v@interface imageLayerViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@end
@implementation imageLayerViewController
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    CALayer *layer = [CALayer layer];
    //为层添加内容因为是ID型所以要转换成id实际上仍是图片
    layer.contents = (id)[UIImage imageNamed:@"1"].CGImage;
    layer.bounds = CGRectMake(0, 0, 200, 200);
    layer.position = CGPointMake(self.imageView.frame.size.width * 0.5, self.imageView.frame.size.height * 0.5);
    [self.imageView.layer addSublayer:layer];
    //创建文字层
    CATextLayer *tLayer = [CATextLayer layer];
    tLayer.fontSize = 24;
    //设置字的颜色
    tLayer.foregroundColor = [UIColor whiteColor].CGColor;
    tLayer.string = @"这是一行文字";
    tLayer.bounds = CGRectMake(0, 0, 200, 40);
    //设置位置
    tLayer.position = CGPointMake(self.imageView.frame.size.width - 50, 50);
    //设置锚点
    tLayer.anchorPoint = CGPointMake(1, 0);
    [self.imageView.layer addSublayer:tLayer];
    //创建图形层
    CAShapeLayer *sLayer = [CAShapeLayer layer];
    /**** 线路径 //设图形路径
    UIBezierPath *bezierPath = [UIBezierPath bezierPath];
    [bezierPath moveToPoint:CGPointMake(50, 50)];
    [bezierPath addLineToPoint:CGPointMake(150, 250)];
    [bezierPath addLineToPoint:CGPointMake(50, 350)];
    [bezierPath closePath];
     */
   /**画曲线 贝塞尔曲线路径
    UIBezierPath *bezierPath = [UIBezierPath bezierPath];
    [bezierPath moveToPoint:CGPointMake(50, 50)];
    [bezierPath addCurveToPoint:CGPointMake(250, 250) controlPoint1:CGPointMake(250, 50) controlPoint2:CGPointMake(50, 250)];
    */
     /** 圆弧或扇形路劲
    UIBezierPath *bezierPath = [UIBezierPath bezierPath];
    //M_PI_2表示弧度2π
    [bezierPath addArcWithCenter:CGPointMake(100, 100) radius:80 startAngle:M_PI_2 endAngle:M_PI clockwise:YES];
    [bezierPath addLineToPoint:CGPointMake(100, 100)];
    [bezierPath closePath]; */
    /**矩形路径
    UIBezierPath *bezierPath = [UIBezierPath bezierPathWithRect:CGRectMake(50, 50, 200, 100)];*/
    /**椭圆路径
    UIBezierPath *bezierPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(50, 50, 200, 100)];*/
     /**圆角路径
    UIBezierPath *bezierPath = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(50, 50, 200, 100)  cornerRadius:15];*/
    //图形路径
    UIBezierPath *bezierPath = [UIBezierPath bezierPath];
    //其间创建路径如上述图形路径等等
    sLayer.path = bezierPath.CGPath;
    //设置描边色
    sLayer.strokeColor = [UIColor redColor].CGColor;
    //设置填充色
sLayer.fillColor = [UIColor greenColor].CGColor;
    sLayer.bounds = CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height);
    sLayer.anchorPoint =CGPointZero;
    [self.imageView.layer addSublayer:sLayer];
}