2018-01-28 iOS基础-小Demo--刮开涂层(刮刮乐

设置刮开后,显示的文字Label UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(7, 50, 400, 400)]; label.text = @"离思五首\n元稹\n曾经沧海难为水,\n除却巫山不是云!\n取次花丛懒回顾,\n半缘修道半缘君!\n"; label.numberOfLines = 0; label.backgroundColor = [UIColor colorWithRed:(arc4random()%173)/346.0 + 0.5 green:(arc4random()%173)/346.0 + 0.5 blue:(arc4random()%173)/346.0 + 0.5 alpha: 1]; label.font = [UIFont systemFontOfSize:30]; label.textAlignment = NSTextAlignmentCenter; [self.view addSubview:label]; 2. 设置遮挡在外面的Image >```obj self.imageView = [[UIImageView alloc]initWithFrame:CGRectMake(7, 50, 400, 400)]; self.imageView.image = [UIImage imageNamed:@"可达鸭"]; [self.view addSubview:self.imageView ];``` 3. 在touchesMoved方法里面实现操作 >```obj `- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ // 触摸任意位置 UITouch *touch = touches.anyObject; // 触摸位置在图片上的坐标 CGPoint cententPoint = [touch locationInView:self.imageView]; // 设置清除点的大小 CGRect rect = CGRectMake(cententPoint.x, cententPoint.y, 20, 20); // 默认是去创建一个透明的视图 UIGraphicsBeginImageContextWithOptions(self.imageView.bounds.size, NO, 0); // 获取上下文(画板) CGContextRef ref = UIGraphicsGetCurrentContext(); // 把imageView的layer映射到上下文中 [self.imageView.layer renderInContext:ref]; // 清除划过的区域 CGContextClearRect(ref, rect); // 获取图片 UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); // 结束图片的画板, (意味着图片在上下文中消失) UIGraphicsEndImageContext(); self.imageView.image = image;``` 作者：云之君兮鹏 链接：https://www.jianshu.com/p/eab521dde13f 來源：简书 著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。