【iOS开发系列】颜色渐变

记录：

//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];  

}