iOS按钮渐变色

使用示例
   UIColor *color1 = UIColorForRGB(0xF46729);
    UIColor *color2 = UIColorForRGB(0xFFAC65);
    UIImage *bgImg = [UIImage gradientColorImageFromColors:@[color1, color2] gradientType:GradientTypeLeftToRight imgSize:self.rightBtn.size];
    [self.rightBtn setBackgroundColor:[UIColor colorWithPatternImage:bgImg]];

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

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

};

@interface UIImage(GradientColor)

+ (UIImage *)gradientColorImageFromColors:(NSArray*)colors gradientType:(GradientType)gradientType imgSize:(CGSize)imgSize;

@end

NS_ASSUME_NONNULL_END

#import "UIImage+GradientColor.h"

@implementation UIImage(GradientColor)

+ (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;

}

@end