渐变颜色过渡

#import "UIView+Extension.h"

@implementation UIView (Extension)

static CAGradientLayer *gradientLayer_;
- (void) insertTransparentGradientFromColor:(UIColor *)fromColor toColor:(UIColor *)toColor fromLocation:(CGFloat)fromLocation toLocation:(CGFloat)toLocation startPoint:(CGPoint)startPoint endPoint:(CGPoint)endPoint {
    CAGradientLayer *layer = [CAGradientLayer layer];
    gradientLayer_ = layer;
    layer.colors = @[(__bridge id)fromColor.CGColor, (__bridge id)toColor.CGColor];
    layer.locations = @[@(fromLocation) ,@(toLocation)];
    layer.frame = self.bounds;
    layer.startPoint = startPoint;
    layer.endPoint = endPoint;
    [self.layer addSublayer:layer];
}
@end

    /**
     *  view 背景颜色的渐变
     *
     *  @param fromColor 从什么颜色
     *  @param toColor 渐变到的颜色
     *  @param fromLocation 从什么位置渐变
     *  @param toLocation 渐变到什么位置
     *  @param startPoint 显示渐变开始的位置
     *  @param endPoint 显示渐变结束的位置
     *
     */
    [self.tmpView insertTransparentGradientFromColor:[UIColor redColor] toColor:[UIColor clearColor] fromLocation:0.5 toLocation:1 startPoint:CGPointMake(0, 0) endPoint:CGPointMake(0, 1)];