ios - Can I detect taps on a controller's tab without being its delegate? -

i've written container controller i'm using inside tab bar controller. container manages stack of controllers uinavigationcontroller, , i'd behave same way navigation controller does, when tab tapped while selected container pops root controller.

i'm not looking solution involves being tab controller's delegate; want container behave same way uinavigationcontroller , automatically when put inside tab controller.

update: respond of scepticism, hoping there might undocumented method uitabbarcontroller calls on uinavigationcontroller implement; however, having put logging in -respondstoselector: method i've seen -_appearancecontainer. however, putting logging in -iskindofclass: shows it's being tested against uinavigationcontroller in several places.

i think found way. tested on navigation controller, think work on custom controller well. use kvo in custom container controller.

 - (void)viewdidload {     [super viewdidload];     [self addobserver:self forkeypath:@"self.tabbarcontroller.selectedviewcontroller" options:nskeyvalueobservingoptionnew | nskeyvalueobservingoptionold context:nil]; }  - (void)observevalueforkeypath:(nsstring *)keypath ofobject:(id)object change:(nsdictionary *)change context:(void *)context {     if ([change[@"old"] isequal:change[@"new"]] && [change[@"new"] isequal:self]) {         nslog(@"nav controller's tab selected again");     }else{         nslog(@"different tab selected");     } }