How to pinch out in iOS simulator when map view is only a portion of the screen?

Only pressing the alt key made the two gray dots representing your fingers appear for me...

Updated Solution:

Holding Option and Command gives you 2 finger vectors that spread out and in. Holding the mouse button down on the way in will pinch in and visa versa for spreading out.

You can move the two gray circles that represent your fingers around the screen by holding Option and Shift and moving the mouse.

Try double tapping with the option key pressed. On the iPhone this causes the MKMapView to zoom out.