ios - Issue with finding the height of the main UIView between a Navigation Controller and Tab Bar -

i had issue of trying find displayed area of view under opaque tab bar , opaque navigation bar. frame evidently closer size of screen (likely includes tab , nav bar) visible , views being hidden.

i know if there official way of finding view size , if there way think programmatically, except maybe subtract tab bar , nav heights (and ruin app in future change apple). apple's own autolayout works fine when pinning bottom of uiview (ie. not go under tab view).

just screen size, , subtract known navigation bars , status bars.

+ (cgfloat) estimateviewheightvertical: (uiviewcontroller*)viewcontroller {     cgrect screen_size = [[uiscreen mainscreen] bounds];     cgfloat screen_height = screen_size.size.height;      cgfloat status_bar_height = [uiapplication sharedapplication].statusbarframe.size.height;     cgfloat tab_bar_controller_height = 0;     cgfloat nav_bar_controller_height = 0;      if (viewcontroller.tabbarcontroller)     {         tab_bar_controller_height = viewcontroller.tabbarcontroller.tabbar.frame.size.height;     }     if (viewcontroller.navigationcontroller)     {         nav_bar_controller_height = viewcontroller.navigationcontroller.navigationbar.frame.size.height;     }     return screen_height - status_bar_height - nav_bar_controller_height - tab_bar_controller_height; }