CAGradientLayer可以方便的处理颜色渐变。
1 self.view.backgroundColor = [UIColor whiteColor];
2 UIImage *image = [UIImage imageNamed:@"mountains.png"]; // 原图
3
4 CALayer *imageLayer = [CALayer layer];
5 imageLayer.borderColor = [UIColor greenColor].CGColor;
6 imageLayer.borderWidth = 2;
7 imageLayer.contents = (id)image.CGImage;
8 imageLayer.bounds = CGRectMake(0, 0, image.size.width, image.size.height);
9 imageLayer.position = CGPointMake(160, 130);
10 [self.view.layer addSublayer:imageLayer]; // 将原图转换为CALayer
11
12 CALayer *reflectionLayer = [CALayer layer]; // 设置倒影层
13 reflectionLayer.contents = imageLayer.contents;
14 reflectionLayer.bounds = imageLayer.bounds;
15 reflectionLayer.position = CGPointMake(160, 330);
16 reflectionLayer.borderColor = imageLayer.borderColor;
17 reflectionLayer.borderWidth = imageLayer.borderWidth;
18 reflectionLayer.opacity = 0.5;
19
20 [reflectionLayer setValue:[NSNumber numberWithFloat:DEGREES_TO_RADIANS(180)] forKeyPath:@"transform.rotation.x"]; // 仅仅将图片层沿X轴反转180度
21
22 CAGradientLayer *gradientLayer = [CAGradientLayer layer]; // 设置渐变效果
23 gradientLayer.bounds = reflectionLayer.bounds;
24 gradientLayer.borderWidth = 2;
25 gradientLayer.borderColor = [UIColor redColor].CGColor;
26 gradientLayer.position = CGPointMake(reflectionLayer.bounds.size.width / 2,
27 reflectionLayer.bounds.size.height * 0.65);
28 gradientLayer.colors = [NSArray arrayWithObjects:
29 (id)[[UIColor greenColor] CGColor],
30 (id)[[UIColor clearColor] CGColor],
31 (id)[[UIColor whiteColor] CGColor], nil];
32 gradientLayer.startPoint = CGPointMake(0.5, 0.5);
33 gradientLayer.endPoint = CGPointMake(0.5, 1.0);
34
35 reflectionLayer.mask = gradientLayer;
36 [self.view.layer addSublayer:reflectionLayer];