创建类（c＃）实例后回调函数结束

Question

如果服务器向它发送一些新的坐标，我写了一些代码在iOS应用程序中绘制某些内容。

我有一个绘制坐标的回调函数。但是当我在这个函数中创建一个类的新实例时，回调出口没有任何错误...

以前有人有这个问题吗？

这里是我的代码，如果这是帮助

CGPath pathtotal; 
    List<CGPath> path; 

    CGPoint initialPoint; 
    CGPoint latestPoint; 

    DrawDrawerDraw drawDrawerDraw; 

    public DrawGuessView(IntPtr handle) : base(handle) 
    { 
     BackgroundColor = UIColor.White; 
     pathtotal = new CGPath(); 

     SocketEventHandler.Add("draw:drawer:draw", onDrawDrawerDraw); 
    } 

    public void onDrawDrawerDraw(dynamic obj) 
    { 
     drawDrawerDraw = (DrawDrawerDraw)obj; 

     for (int i = 0; i <= drawDrawerDraw.coords.Count; i++) 
     { 
      if (initialPoint.X != (nfloat)drawDrawerDraw.coords[i].x0 && initialPoint.Y != (nfloat)drawDrawerDraw.coords[i].y0) 
      { 
       path[i] = new CGPath(); 
      } 

      initialPoint.X = (nfloat)drawDrawerDraw.coords[i].x0; 
      initialPoint.Y = (nfloat)drawDrawerDraw.coords[i].y0; 

      latestPoint.X = (nfloat)drawDrawerDraw.coords[i].x1; 
      latestPoint.Y = (nfloat)drawDrawerDraw.coords[i].y1; 

      //add lines to the touch points 
      if (path[i].IsEmpty) 
      { 
       path[i].AddLines(new CGPoint[] { initialPoint, latestPoint }); 
      } 
      else 
      { 
       path[i].AddLineToPoint(latestPoint); 
      } 
     } 

     SetNeedsDisplay(); 
    } 

    public override void Draw(CGRect rect) 
    { 
     base.Draw(rect); 

     try 
     { 
      foreach (var item in path) 
      { 
       if (!initialPoint.IsEmpty) 
       { 
        //get graphics context 
        using (CGContext g = UIGraphics.GetCurrentContext()) 
        { 
         //set up drawing attributes 
         g.SetLineWidth(2); 
         UIColor.Black.SetStroke(); 

         //add geometry to graphics context and draw it 
         pathtotal.AddPath(item); 

         g.AddPath(pathtotal); 
         g.DrawPath(CGPathDrawingMode.Stroke); 
        } 
       } 
      } 
     } 
     catch (Exception e) { } 
    } 
} 

Answer 1

有需要修改两点。

1. 初始化path在DrawGuessView方法

   public DrawGuessView(IntPtr handle) : base(handle) 
   { 
       BackgroundColor = UIColor.White; 
       pathtotal = new CGPath(); 
       List<CGPath> path = new List<CGPath>(); 
       SocketEventHandler.Add("draw:drawer:draw", onDrawDrawerDraw); 
   } 
   

2. path[i] = new CGPath()将导致ArgumentOutOfRangeException，我们不能在列表通过这种方式设定值的项目。

   修改循环

   CGPath pathItem = null; 
   for (int i = 0; i <= drawDrawerDraw.coords.Count; i++) 
   { 
       if (initialPoint.X != (nfloat)drawDrawerDraw.coords[i].x0 && initialPoint.Y != (nfloat)drawDrawerDraw.coords[i].y0) 
       { 
        pathItem = new CGPath(); 
       } 
   
       initialPoint.X = (nfloat)drawDrawerDraw.coords[i].x0; 
       initialPoint.Y = (nfloat)drawDrawerDraw.coords[i].y0; 
   
       latestPoint.X = (nfloat)drawDrawerDraw.coords[i].x1; 
       latestPoint.Y = (nfloat)drawDrawerDraw.coords[i].y1; 
   
       //add lines to the touch points 
       if (pathItem.IsEmpty) 
       { 
        pathItem.AddLines(new CGPoint[] { initialPoint, latestPoint }); 
       } 
       else 
       { 
        pathItem.AddLineToPoint(latestPoint); 
       } 
       path.Add(pathItem); 
   }