title: middlePoint in CGContextAddArc?
body: <p>i am drawing Arc  through CGCOntext.I want to draw a string in the center Point of Arc.how can i fond the center point in the Arc which has been drawn through CGContext.</p>
  
  <pre><code>              CGContextSetAlpha(ctx, 0.5);
  CGContextSetRGBFillColor(ctx, color.red, color.green, color.blue, color.alpha );
  CGContextMoveToPoint(ctx, cX, cY);
  CGContextAddArc(ctx, cX, cY, radious+10, (startDeg-90)*M_PI/180.0, (endDeg-90)*M_PI/180.0, 0);
  CGContextClosePath(ctx);
  CGContextFillPath(ctx); 
  </code></pre>