iOS-设置图片渐变色

淘宝电商类图片渐变设置

.h文件

typedef NS_ENUM(NSUInteger, GradientType) {
    GradientTypeTopToBottom = 0,//从上到下
    GradientTypeLeftToRight = 1,//从左到右
    GradientTypeUpleftToLowright = 2,//左上到右下
    GradientTypeUprightToLowleft = 3,//右上到左下 };

/**  设置图片的渐变色(颜色->图片)

 @param colors 渐变颜色数组  @param gradientType 渐变样式  @param imgSize 图片大小  @return 颜色->图片  */
+ (UIImage *)gradientColorImageFromColors:(NSArray*)colors gradientType:(GradientType)gradientType imgSize:(CGSize)imgSize;

.m文件

+ (UIImage *)gradientColorImageFromColors:(NSArray*)colors gradientType:(GradientType)gradientType imgSize:(CGSize)imgSize {
    NSMutableArray *ar = [NSMutableArray array];
    for(UIColor *c in colors) {
        [ar addObject:(id)c.CGColor];
    }
    UIGraphicsBeginImageContextWithOptions(imgSize, YES, 1);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);
    CGColorSpaceRef colorSpace = CGColorGetColorSpace([[colors lastObject] CGColor]);
    CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (CFArrayRef)ar, NULL);
    CGPoint start;
    CGPoint end;
    switch (gradientType) {
        case GradientTypeTopToBottom:
            start = CGPointMake(0.0, 0.0);
            end = CGPointMake(0.0, imgSize.height);
            break;
        case GradientTypeLeftToRight:
            start = CGPointMake(0.0, 0.0);
            end = CGPointMake(imgSize.width, 0.0);
            break;
        case GradientTypeUpleftToLowright:
            start = CGPointMake(0.0, 0.0);
            end = CGPointMake(imgSize.width, imgSize.height);
            break;
        case GradientTypeUprightToLowleft:
            start = CGPointMake(imgSize.width, 0.0);
            end = CGPointMake(0.0, imgSize.height);
            break;
        default:
            break;
    }
    CGContextDrawLinearGradient(context, gradient, start, end,kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    CGGradientRelease(gradient);
    CGContextRestoreGState(context);
    CGColorSpaceRelease(colorSpace);
    UIGraphicsEndImageContext();
    return image;
}

引用
#import “UIImage+Category.h”

UIImage *bgImg = [UIImage gradientColorImageFromColors:@[kColor56B825,kColorB4EC51] gradientType:GradientTypeTopToBottom imgSize:CGSizeMake(ScreenW, HGADPT(200))];