转载
UIBezierPath通过

• (void)addArcWithCenter:(CGPoint)center radius:(CGFloat)radius startAngle:(CGFloat)startAngle endAngle:(CGFloat)endAngle clockwise:(BOOL)clockwise

可以画出一段弧线。

看下各个参数的意义：

center：圆心的坐标

radius：半径

startAngle：起始的弧度

endAngle：圆弧结束的弧度

clockwise：YES为顺时针，No为逆时针

方法里面主要是理解startAngle与endAngle，刚开始我搞不清楚一段圆弧从哪算起始和终止，比如弧度为0的话，是从上下左右哪个点开始算

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[objc] view plaincopy

<embed id="ZeroClipboardMovie_1" src="http://csdnimg.cn/public/highlighter/ZeroClipboard.swf" loop="false" menu="false" quality="best" bgcolor="#ffffff" width="16" height="16" name="ZeroClipboardMovie_1" align="middle" allowscriptaccess="always" allowfullscreen="false" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" flashvars="id=1&width=16&height=16" wmode="transparent" style="box-sizing: border-box;">

1. CAShapeLayer *layer = [[CAShapeLayer alloc] init];

2. layer.name = @"Radius";

3. CGFloat lineWidth = 10;

4. UIBezierPath *path = [UIBezierPath bezierPath];

5. path.lineWidth = lineWidth;

6. path.lineCapStyle = kCGLineCapButt;

7. CGPoint center = CGPointMake(self.bounds.size.width/2, self.bounds.size.height/2);

8. CGFloat radius = (self.bounds.size.width - lineWidth)/2;

9. CGFloat startAngle = -((float)M_PI)/7; //

10. CGFloat endAngle = ((float)M_PI)-startAngle ;

11. [[UIColor whiteColor] set];

12. [path addArcWithCenter:center radius:radius startAngle:startAngle endAngle:endAngle clockwise:YES];

13. [path stroke];

14. [path closePath];

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