上面我们只是绘制渐变到图形上下文，实际开发中有时候我们还需要填充对应的渐变色，例如现在绘制了一个矩形，如何填充成渐变色呢？在此可以利用渐变裁切来完成（当然利用层CALayer更加方便但这不在今天的话题讨论范围内），特别说明一下区域裁切并不仅仅适用于渐变填充，对于其他图形绘制仍然适用，并且注意裁切只能限于矩形裁切。
-(void)drawRectWithLinearGradientFill:(CGContextRef)context{ CGColorSpaceRef colorSpace=CGColorSpaceCreateDeviceRGB(); //裁切处一块矩形用于显示，注意必须先裁切再调用渐变 //CGContextClipToRect(context, CGRectMake(20, 50, 280, 300)); //裁切还可以使用UIKit中对应的方法 UIRectClip(CGRectMake(20, 50, 280, 300)); CGFloat compoents[12]={ 248.0/255.0,86.0/255.0,86.0/255.0,1, 249.0/255.0,127.0/255.0,127.0/255.0,1, 1.0,1.0,1.0,1.0 }; CGFloat locations[3]={0,0.3,1.0}; CGGradientRef gradient= CGGradientCreateWithColorComponents(colorSpace, compoents, locations, 3); CGContextDrawLinearGradient(context, gradient, CGPointMake(20, 50), CGPointMake(300, 300), kCGGradientDrawsAfterEndLocation); //释放颜色空间 CGColorSpaceRelease(colorSpace); }运行效果：
常用的图形上下文状态设置上面基本都用到了，我们不再一一解释，这里着重说一下叠加模式和填充模式，初学者对于这两个状态设置往往容易产生疑惑。
叠加模式使用Quartz 2D绘图时后面绘制的图像会覆盖前面的，默认情况下如果前面的被覆盖后将看不到后面的内容，但是有时候这个结果并不是我们想要的，因此在Quartz 2D中提供了填充模式供开发者配置调整。由于填充模式类别特别多，因此下面以一个例子来说明：
-(void)drawRectByUIKitWithContext2:(CGContextRef)context{ CGRect rect= CGRectMake(0, 130.0, 320.0, 50.0); CGRect rect1= CGRectMake(0, 390.0, 320.0, 50.0); CGRect rect2=CGRectMake(20, 50.0, 10.0, 250.0); CGRect rect3=CGRectMake(40.0, 50.0, 10.0, 250.0); CGRect rect4=CGRectMake(60.0, 50.0, 10.0, 250.0); CGRect rect5=CGRectMake(80.0, 50.0, 10.0, 250.0); CGRect rect6=CGRectMake(100.0, 50.0, 10.0, 250.0); CGRect rect7=CGRectMake(120.0, 50.0, 10.0, 250.0); CGRect rect8=CGRectMake(140.0, 50.0, 10.0, 250.0); CGRect rect9=CGRectMake(160.0, 50.0, 10.0, 250.0); CGRect rect10=CGRectMake(180.0, 50.0, 10.0, 250.0); CGRect rect11=CGRectMake(200.0, 50.0, 10.0, 250.0); CGRect rect12=CGRectMake(220.0, 50.0, 10.0, 250.0); CGRect rect13=CGRectMake(240.0, 50.0, 10.0, 250.0); CGRect rect14=CGRectMake(260.0, 50.0, 10.0, 250.0); CGRect rect15=CGRectMake(280.0, 50.0, 10.0, 250.0); CGRect rect16=CGRectMake(30.0, 310.0, 10.0, 250.0); CGRect rect17=CGRectMake(50.0, 310.0, 10.0, 250.0); CGRect rect18=CGRectMake(70.0, 310.0, 10.0, 250.0); CGRect rect19=CGRectMake(90.0, 310.0, 10.0, 250.0); CGRect rect20=CGRectMake(110.0, 310.0, 10.0, 250.0); CGRect rect21=CGRectMake(130.0, 310.0, 10.0, 250.0); CGRect rect22=CGRectMake(150.0, 310.0, 10.0, 250.0); CGRect rect23=CGRectMake(170.0, 310.0, 10.0, 250.0); CGRect rect24=CGRectMake(190.0, 310.0, 10.0, 250.0); CGRect rect25=CGRectMake(210.0, 310.0, 10.0, 250.0); CGRect rect26=CGRectMake(230.0, 310.0, 10.0, 250.0); CGRect rect27=CGRectMake(250.0, 310.0, 10.0, 250.0); CGRect rect28=CGRectMake(270.0, 310.0, 10.0, 250.0); CGRect rect29=CGRectMake(290.0, 310.0, 10.0, 250.0); [[UIColor yellowColor]set]; UIRectFill(rect); [[UIColor greenColor]setFill]; UIRectFill(rect1); [[UIColor redColor]setFill]; UIRectFillUsingBlendMode(rect2, kCGBlendModeClear); UIRectFillUsingBlendMode(rect3, kCGBlendModeColor); UIRectFillUsingBlendMode(rect4, kCGBlendModeColorBurn); UIRectFillUsingBlendMode(rect5, kCGBlendModeColorDodge); UIRectFillUsingBlendMode(rect6, kCGBlendModeCopy); UIRectFillUsingBlendMode(rect7, kCGBlendModeDarken); UIRectFillUsingBlendMode(rect8, kCGBlendModeDestinationAtop); UIRectFillUsingBlendMode(rect9, kCGBlendModeDestinationIn); UIRectFillUsingBlendMode(rect10, kCGBlendModeDestinationOut); UIRectFillUsingBlendMode(rect11, kCGBlendModeDestinationOver); UIRectFillUsingBlendMode(rect12, kCGBlendModeDifference); UIRectFillUsingBlendMode(rect13, kCGBlendModeExclusion); UIRectFillUsingBlendMode(rect14, kCGBlendModeHardLight); UIRectFillUsingBlendMode(rect15, kCGBlendModeHue); UIRectFillUsingBlendMode(rect16, kCGBlendModeLighten); UIRectFillUsingBlendMode(rect17, kCGBlendModeLuminosity); UIRectFillUsingBlendMode(rect18, kCGBlendModeMultiply); UIRectFillUsingBlendMode(rect19, kCGBlendModeNormal); UIRectFillUsingBlendMode(rect20, kCGBlendModeOverlay); UIRectFillUsingBlendMode(rect21, kCGBlendModePlusDarker); UIRectFillUsingBlendMode(rect22, kCGBlendModePlusLighter); UIRectFillUsingBlendMode(rect23, kCGBlendModeSaturation); UIRectFillUsingBlendMode(rect24, kCGBlendModeScreen); UIRectFillUsingBlendMode(rect25, kCGBlendModeSoftLight); UIRectFillUsingBlendMode(rect26, kCGBlendModeSourceAtop); UIRectFillUsingBlendMode(rect27, kCGBlendModeSourceIn); UIRectFillUsingBlendMode(rect28, kCGBlendModeSourceOut); UIRectFillUsingBlendMode(rect29, kCGBlendModeXOR); }运行效果：
