CGContextAddArcToPoint和CGContextAddArc

比较难的是CGContextAddArcToPoint

代码如下：

CGContextRef context=UIGraphicsGetCurrentContext();  
CGContextSetRGBStrokeColor(context,1,0,0,1);  
CGContextMoveToPoint(context,150,50);  
CGContextAddLineToPoint(context,100,80);  
CGContextAddLineToPoint(context,130,150);  
 
CGContextMoveToPoint(context,150,50);//圆弧的起始点  
CGContextAddArcToPoint(context,100,80,130,150,50);  
CGContextStrokePath(context);  

image.png