textFieldShouldReturn not being called in iOS
I had the exact same issue and it was because I forgot to set the delegate for the text field in interface builder to 'files owner'.
I had the same problem and, as Warren Crowther suggested, I managed to solve it by holding down CTRL and dragging from the TextBox to the "File's Owner" label.
(Gosh, I miss Visual Studio sometimes...!!)
(Apologies for repeating what's already been said, but I thought a screenshot might be useful !)
I had the delegate set and everything. But I was using a UITextView instead of UITextfield...
Perhaps this will help someone trying to figure why delegate methods are not fired.