title: Error: "Invalid operands to binary /"
body: <p>I'm using this code for the moving, scaling and rotating an UIImageView. </p>
  
  <pre><code>- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
  
      CGPoint currentTouch1;
      CGPoint currentTouch2;
      NSArray *allTouches = [touches allObjects];
      UITouch* t;
      float scale,rotation;
  
      if([[event allTouches] count]==1){
          t=[[[event allTouches] allObjects] objectAtIndex:0];
          if (CGRectContainsPoint([Birdie frame], [[allTouches objectAtIndex:0] locationInView:self.view]))
          { 
              touch2=[t locationInView:nil];
              Birdie.center=CGPointMake(Birdie.center.x+touch2.x-touch1.x,Birdie.center.y+touch2.y-touch1.y);
              touch1=touch2;
          }
      }
      else if([[event allTouches] count]==2)
      {
          t=[[[event allTouches] allObjects] objectAtIndex:0];
          currentTouch1=[t locationInView:nil];
  
          t=[[[event allTouches] allObjects] objectAtIndex:1];
          currentTouch2=[t locationInView:nil];
  
  
          scale = [self distance:currentTouch1 toPoint:currentTouch2] / [self distance:touch1 toPoint:touch2];
          rotation=atan2(currentTouch2.y-currentTouch1.y, currentTouch2.x-currentTouch1.x)-atan2(touch2.y-touch1.y,touch2.x-touch1.x);
          if(isnan(scale)){
              scale=1.0f;
          }
          NSLog(@"rotation %f",rotation);
  
          NSLog(@"scale %f",scale);
  
          if (CGRectContainsPoint([Birdie frame], [[allTouches objectAtIndex:0] locationInView:self.view]) &amp;&amp;
              CGRectContainsPoint([Birdie frame], [[allTouches objectAtIndex:1] locationInView:self.view]))
          {
  
              Birdie.transform=CGAffineTransformScale(Birdie.transform, scale,scale);
              Birdie.transform=CGAffineTransformRotate(Birdie.transform, rotation);
          }
          else // In case of scaling or rotating the background imageView
          {
              imageView.transform=CGAffineTransformScale(imageView.transform, scale,scale);
              imageView.transform=CGAffineTransformRotate(imageView.transform, rotation);
          }
  
          touch1=currentTouch1;
          touch2=currentTouch2;
      }
  }
  
  -(double)distance:(CGPoint)point1 toPoint:(CGPoint)point2
  {
      return sqrt(fabs(point1.x - point2.x) + fabs(point1.y - point2.y));
  }
  </code></pre>
  
  <p>However I get one error the whole time, Invalid operands to binary /.
  I get this error on the next line:</p>
  
  <pre><code>    scale = [self distance:currentTouch1 toPoint:currentTouch2] / [self distance:touch1 toPoint:touch2];
  </code></pre>