ios绘制渐变色图片

/**
*  绘制渐变色的矩形UIImage
*
*  @param bounds       UIImage的bounds
*  @param colors       渐变色数组，可以设置两种颜色
*  @param gradientType 渐变的方式：0:水平渐变   1:竖直渐变   2:向下对角线渐变   3:向上对角线渐变
*
*  @return 渐变色的UIImage
*/
+ (UIImage*)createGradientRectImageWithBounds:(CGRect)bounds Colors:(NSArray*)colors GradientType:(int)gradientType{
    NSMutableArray *cgcolorArr = [NSMutableArray array];
    for(UIColor *col in colors) {
        [cgcolorArr addObject:(id)col.CGColor];
    }
    UIGraphicsBeginImageContextWithOptions(bounds.size, YES, 1);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);
    CGColorSpaceRef colorSpace = CGColorGetColorSpace([[colors lastObject] CGColor]);
    CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (CFArrayRef)cgcolorArr, NULL);
    CGPoint startPoint = CGPointMake(0.0, 0.0);
    if (gradientType == 3) {
        startPoint = CGPointMake(0.0, bounds.size.height);
    }
    CGPoint endPoint = CGPointZero;
    switch (gradientType) {
        case 0:
            endPoint = CGPointMake(bounds.size.width, 0.0);
            break;
        case 1:
            endPoint = CGPointMake(0.0, bounds.size.width);
            break;
        case 2:
            endPoint = CGPointMake(bounds.size.width, bounds.size.height);
            break;
        case 3:
            endPoint = CGPointMake(bounds.size.width, 0.0);
            break;
        default:
            break;
    }
    CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    CGGradientRelease(gradient);
    CGContextRestoreGState(context);
    CGColorSpaceRelease(colorSpace);
    UIGraphicsEndImageContext();
    return image;
}