UserInteraction = NO does not appear to be working for my app

Question

if I do this:
self.view.userInteractionEnabled = NO;
[progressView startAnimating];
BOOL status = [call a function here];
[progressView stopAnimating];
self.view.userInteractionEnabled = YES;
The progressView does work as expected, but the user can continue to crash the program by interacting like nothing was set to prevent them. I even tried setting this on the navigationController. Nothing seems to be working.
This results in the program crashing ans odd things happening on the device.
Does anyone have any idea what I can do to eliminate user interaction and then enable it bracketing a function call?

Answer 1

I must be doing something wrong. The description for the begin/end IgnoringInteractionEvents looks like it would do the trick for me. (but then I thought that setUserInteractionEnabled should work too)
Even after bracketing the call with both of these - the User can still click the 'back' button to pop the view and thus crash the program. All while the progressView is happily spinning along. I dont set 'end' until After I stop animating and the animating is going on.
[[UIApplication sharedApplication] beginIgnoringInteractionEvents];
[self.view setUserInteractionEnabled:NO];
[progressView startAnimating];
[call a function here for uploading or downloading data using ftp];
self.view.userInteractionEnabled = YES];
//[UIApplication sharedApplication] endIgnoringInteractionEvents];
[open another controller]
[push the controller]
[release the new controller]
Note - I've even disabled the end statement to test this...
What's happening is the user can still click back to pop the current controller
and crash the program. If left alone it creates the new controller and THEN ignores interactions. I need to prevent interaction immediately. I thought perhaps the second call is being made immediately and reenabling, but this is not the case because I never call the 'end' statement in this test.
Any ideas? Should I be looking toward a Thread solution for the function call that I need to protect?
This is pretty bad for my app. If I cannot protect this from user interactions while this is going on the app breaks, and then as a bonus it seems to do odd things like screen shots, open Safari. So it must be taken care of or removed.
I'm a little nervous right now because I am surprised that no level of setting beginIgnoringInteractionEvents, or setUserInteractionEnabled seems to keep the user from simply pressing the back button on the current controller while the other function is running.