CAGradientLayer 实现渐变色

UIView*showView = [[UIViewalloc]initWithFrame:CGRectMake(100,100,100,100)];

[self.viewaddSubview:showView];

showView.backgroundColor= [UIColorredColor];

showView.alpha=0.5;

//创建一个gradientLayer

CAGradientLayer*gradientLayer =  [CAGradientLayerlayer];

gradientLayer.frame= showView.bounds;

[gradientLayersetColors:[NSArrayarrayWithObjects:

(id)[[UIColorredColor]CGColor],

(id)[[UIColoryellowColor]CGColor],nil]];

[gradientLayersetLocations:@[@0.5,@0.9,@1]];

[gradientLayersetStartPoint:CGPointMake(0.5,1)];

[gradientLayersetEndPoint:CGPointMake(0.5,0)];

[showView.layeraddSublayer:gradientLayer];

效果如下图：