//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);