code实现透明度渐变和颜色渐变的view

最近用code写了些view上的渐变效果，使得app的UI特效不必全部依赖美工出的图片。

效果如下：



主要用到了Layer上的渐变层，核心代码如下，关于CALayer的使用可参考

[objc] view
plaincopyprint?





//Transparent Gradient Layer

- (void) insertTransparentGradient {

UIColor *colorOne = [UIColor colorWithRed:(33/255.0) green:(33/255.0) blue:(33/255.0) alpha:0.0];

UIColor *colorTwo = [UIColor colorWithRed:(33/255.0) green:(33/255.0) blue:(33/255.0) alpha:1.0];

NSArray *colors = [NSArray arrayWithObjects:(id)colorOne.CGColor, colorTwo.CGColor, nil nil];

NSNumber *stopOne = [NSNumber numberWithFloat:0.0];

NSNumber *stopTwo = [NSNumber numberWithFloat:1.0];

NSArray *locations = [NSArray arrayWithObjects:stopOne, stopTwo, nil nil];

//crate gradient layer

CAGradientLayer *headerLayer = [CAGradientLayer layer];

headerLayer.colors = colors;

headerLayer.locations = locations;

headerLayer.frame = self.bounds;

[self.layer insertSublayer:headerLayer atIndex:0];

}

//color gradient layer

- (void) insertColorGradient {

UIColor *colorOne = [UIColor colorWithRed:(255/255.0) green:(255/255.0) blue:(255/255.0) alpha:1.0];

UIColor *colorTwo = [UIColor colorWithRed:(33/255.0) green:(33/255.0) blue:(33/255.0) alpha:1.0];

NSArray *colors = [NSArray arrayWithObjects:(id)colorOne.CGColor, colorTwo.CGColor, nil nil];

NSNumber *stopOne = [NSNumber numberWithFloat:0.0];

NSNumber *stopTwo = [NSNumber numberWithFloat:1.0];

NSArray *locations = [NSArray arrayWithObjects:stopOne, stopTwo, nil nil];

CAGradientLayer *headerLayer = [CAGradientLayer layer];

headerLayer.colors = colors;

headerLayer.locations = locations;

headerLayer.frame = self.bounds;

[self.layer insertSublayer:headerLayer above:0];

}