You should modify your ahandlePinch1
method so that you don't reduce the size of the image below a certain amount. It is almost certainly getting so small that it can no longer detect two distinct touches (which are required for the pinch gesture).
Apple generally recommend allowing a minimum of 44x44 pts as a touchable area, so I would suggest you stop your image from resizing below 88x88.
Alternatively, if you actually need your image to be less than that then you should add the gesture recognizer to a different view (perhaps the superview), rather than the image itself.