CALayer创建图层和遮挡层应用

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CALayer创建图层

// 创建图层    CALayer *layer = [CALayer layer];    layer.frame = CGRectMake(50, 50, 200, 200);    layer.backgroundColor = [UIColor redColor].CGColor;    // 设置图层内容    layer.contents = (id)[UIImage imageNamed:@"阿狸头像"].CGImage;    [self.view.layer addSublayer:layer];

优点：比UIImageView省内存。

二CALayer遮挡层

//图片在图层的下面你看到的图是通过第一层图形的形状看到的第二张图

#import "ViewController.h"@interface ViewController ()@property(nonatomic,strong) CALayer *imageLayer;@property(nonatomic,strong) CALayer *maskLayer;@property(nonatomic,strong) UIImage *imageContents;@property(nonatomic,strong) UIImage *maskCountents;@end

 self.view.backgroundColor = [UIColor grayColor];        ///底图    self.imageContents = [UIImage imageNamed:@"02"];    ///显示底图的图    self.maskCountents = [UIImage imageNamed:@"maskLayerContents@2x"];            ///图片Layer    self.imageLayer = [CALayer layer];    self.imageLayer.frame = CGRectMake(0, 64, self.view.frame.size.width, self.view.frame.size.height - 64);    ///设置    self.imageLayer.contents = (__bridge id _Nullable)((self.imageContents.CGImage));    [self.view.layer addSublayer:self.imageLayer];            ///遮罩Layer    self.maskLayer = [CALayer layer];    self.maskLayer.frame = CGRectMake(0, 64, 200, 200);    self.maskLayer.contents = (__bridge id _Nullable)((self.maskCountents.CGImage));        //    根据alpha通道 来选择遮罩的地方 黑色全通过，白色全不通过    self.imageLayer.mask = self.maskLayer;        [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(timerClick) userInfo:nil repeats:YES];

- (void)timerClick{    CGFloat x = arc4random()%(375-200);    CGFloat y = arc4random()%(667-200-64);        ///随机取图块    self.maskLayer.frame = CGRectMake(x, y, 200, 200);}

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