代码如下
typedef enum {GradientLayerKindLeftRight = 2000,GradientLayerKindUpDown,GradientLayerKindLBRT,//左下-右上GradientLayerKindLTRB //左上-右下
}GradientLayerKind;//--------------------------------------------------------------//  创建矩形渐变图层//// @param frame      渐变图层的frame//  @param startColor 起始颜色（设置起止颜色的时候可以设置颜色的透明度达到透明度渐变的效果）//  @param endColor   终止颜色//  @param kind       渐变类型//                    GradientLayerKindLeftRight = 1,//左-右//                    GradientLayerKindUpDown,       //上-下//                    GradientLayerKindLBRT,         //左下-右上//                    GradientLayerKindLTRB          //左上-右下//  @return 渐变色layer//----------------------------------------------------------
- (CALayer*)ct_getGradientLayerWithFrame:(CGRect)frame StartColor:(UIColor *)startColor endColor:(UIColor*)endColor andKind:(GradientLayerKind)kind{//渐变图层CAGradientLayer *gradientLayer =  [CAGradientLayer layer];gradientLayer.frame = frame;[gradientLayer setColors:[NSArray arrayWithObjects:(id)[startColor CGColor],(id)[endColor CGColor], nil]];if (kind == GradientLayerKindUpDown) {[gradientLayer setLocations:@[@0,@1]];[gradientLayer setStartPoint:CGPointMake(0.5, 0)];[gradientLayer setEndPoint:CGPointMake(0.5, 1)];}else if (kind == GradientLayerKindLeftRight){[gradientLayer setLocations:@[@0,@1]];[gradientLayer setStartPoint:CGPointMake(0, 0.5)];[gradientLayer setEndPoint:CGPointMake(1, 0.5)];}else if (kind == GradientLayerKindLTRB){[gradientLayer setLocations:@[@0,@1]];[gradientLayer setStartPoint:CGPointMake(0, 0)];[gradientLayer setEndPoint:CGPointMake(1, 1)];}else if (kind == GradientLayerKindLBRT){[gradientLayer setLocations:@[@0,@1]];[gradientLayer setStartPoint:CGPointMake(0, 1)];[gradientLayer setEndPoint:CGPointMake(1, 0)];}return gradientLayer;}
使用：viewcontroller的viewdidload中for (int i = 0; i < 4; i++) {NSInteger hang = i%2,lie=i/2;CGFloat w=self.view.frame.size.width/2.0,h=(self.view.frame.size.height-64)/2.0;CGRect frame = CGRectMake(hang*w, lie*h, w, h);[self.view.layer addSublayer:[self ct_getGradientLayerWithFrame:frame StartColor:[self rgb:0 g:0 b:0 a:0.9] endColor:[self rgb:255 g:255 b:255 a:0.1] andKind:i+2000]];}
设置颜色方法：
-(UIColor*)rgb:(NSInteger)r g:(NSInteger)g b:(NSInteger)b a:(CGFloat)alpha{return [UIColor colorWithRed:r%256/256.0 green:g%256/256.0 blue:b%256/256.0 alpha:alpha];}
效果图如图所示：（可以发现图层下的label和按钮都可以显示，并且按钮的点击事件正常响应）