CG

//设置线的宽度

CGContextSetLineWidth(ctx, 12);

//设置线的连接处 （拐点）

CGContextSetLineJoin(ctx, kCGLineJoinRound )

/* Line join styles. */

enum CGLineJoin {

kCGLineJoinMiter,

kCGLineJoinRound,//圆滑的

kCGLineJoinBevel

};

//设置线的端点

CGContextSetLineCap(ctx, kCGLineCapButt); 设置 线的端点样式

enum CGLineCap {

kCGLineCapButt,//和第三个一样 。。。。不懂

kCGLineCapRound,//端点是圆的

kCGLineCapSquare //正方形

};

typedef enum CGLineCap CGLineCap;

//以渐变色填充当前的线

//list of components

CGFloat components[8] = {

0.0, 0.0, 1.0, 1.0,     // Start color - Blue

1.0, 0.0, 1.0, 1.0 };   // End color - Violet

CGColorSpaceRef baseSpace = CGColorSpaceCreateDeviceRGB();

CGGradientRef gradient = CGGradientCreateWithColorComponents(baseSpace, components, NULL, 2);

CGColorSpaceRelease(baseSpace), baseSpace = NULL;

//Gradient direction

CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));

CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));

//Draw the gradient

CGContextDrawLinearGradient(ctx, gradient, startPoint, endPoint, 0);

CGGradientRelease(gradient), gradient = NULL;

CGContextRestoreGState(ctx);