两段代码，首先是使用方法

CGContextRef context = UIGraphicsGetCurrentContext();    NSArray *colors = [NSArray arrayWithObjects:                       [UIColor colorWithRed:225.0 / 255.0 green:225.0 / 255.0 blue:225.0 / 255.0 alpha:1.0],                       [UIColor colorWithRed:168.0 / 255.0 green:168.0 / 255.0 blue:168.0 / 255.0 alpha:1.0],                       nil];    [self _drawGradientColor:context                        rect:CGRectMake(rX, rY, rW, rH)                     options:kCGGradientDrawsAfterEndLocation                      colors:colors];    CGContextStrokePath(context);// 描线,即绘制形状    CGContextFillPath(context);// 填充形状内的颜色

在一段就是绘制背景色渐变的矩形

/** * 绘制背景色渐变的矩形，p_colors渐变颜色设置，集合中存储UIColor对象（创建Color时一定用三原色来创建） **/- (void)_drawGradientColor:(CGContextRef)p_context                      rect:(CGRect)p_clipRect                   options:(CGGradientDrawingOptions)p_options                    colors:(NSArray *)p_colors {    CGContextSaveGState(p_context);// 保持住现在的context    CGContextClipToRect(p_context, p_clipRect);// 截取对应的context    int colorCount = p_colors.count;    int numOfComponents = 4;    CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();    CGFloat colorComponents[colorCount * numOfComponents];    for (int i = 0; i < colorCount; i++) {        UIColor *color = p_colors[i];        CGColorRef temcolorRef = color.CGColor;        const CGFloat *components = CGColorGetComponents(temcolorRef);        for (int j = 0; j < numOfComponents; ++j) {            colorComponents[i * numOfComponents + j] = components[j];        }    }    CGGradientRef gradient =  CGGradientCreateWithColorComponents(rgb, colorComponents, NULL, colorCount);    CGColorSpaceRelease(rgb);    CGPoint startPoint = p_clipRect.origin;    CGPoint endPoint = CGPointMake(CGRectGetMinX(p_clipRect), CGRectGetMaxY(p_clipRect));    CGContextDrawLinearGradient(p_context, gradient, startPoint, endPoint, p_options);    CGGradientRelease(gradient);    CGContextRestoreGState(p_context);// 恢复到之前的context}

还有一种实现方式

CAGradientLayer *gradient = [CAGradientLayer layer];gradient.frame = CGRectMake(rX, rY, rW, rH);gradient.colors = [NSArray arrayWithObjects:                       (id)[UIColor blackColor].CGColor,                       (id)[UIColor grayColor].CGColor,                       (id)[UIColor blackColor].CGColor,                        nil];[self.view.layer insertSublayer:gradient atIndex:0];

#import <QuartzCore/QuartzCore.h>

此文的完成用到了四位老师的文章，在此表示感谢。