之前做过类似的功能，现在记录一下，来来来。。。
效果图：
说明===========================
方法1:
说明：无返回值
用法：直接调用方法。原理是在view的layer层添加。
方法2:
说明：先返回一个Image，再使用
用法：若是image背景，直接使用，若是color背景，用 [UIColor colorWithPatternImage:image]即可。
代码===========================
方法1:
-(void)createByCAGradientLayer:(UIColor *)startColor endColor:(UIColor *)endColor layerFrame:(CGRect)frame direction:(GradientType)direction{CAGradientLayer *layer = [CAGradientLayer new];//存放渐变的颜色的数组layer.colors = @[(__bridge id)startColor.CGColor, (__bridge id)endColor.CGColor];//起点和终点表示的坐标系位置，(0,0)表示左上角，(1,1)表示右下角switch (direction) {case GradientTypeTopToBottom:layer.startPoint = CGPointMake(0.0, 0.0);layer.endPoint = CGPointMake(0.0, 1);break;case GradientTypeLeftToRight:layer.startPoint = CGPointMake(0.0, 0.0);layer.endPoint = CGPointMake(1, 0.0);break;default:break;}layer.frame = frame;[self.view.layer addSublayer:layer];}
方法2:
- (UIImage *)getGradientImageFromColors:(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;default:break;}CGContextDrawLinearGradient(context, gradient, start, end, kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation);UIImage *image = UIGraphicsGetImageFromCurrentImageContext();CGGradientRelease(gradient);CGContextRestoreGState(context);CGColorSpaceRelease(colorSpace);UIGraphicsEndImageContext();return image;
}
这里有个方向枚举，用来表示垂直还是水平
typedef NS_ENUM(NSUInteger, GradientType) {GradientTypeTopToBottom = 0,//从上到下GradientTypeLeftToRight = 1,//从左到右
};