I am using a custom UIAlertView with UITextField to get password from the user.
UIAlertView
UITextField
I have been told that this custom view may cause my App to get
Quoting from the class reference
The UIAlertView class is intended to be used as-is and does not support subclassing. The view hierarchy for this class is private and must not be modified.
The last sentence appears to me that they don't want developers modifying the views.