ios - how to set image on default back button of navigation bar -

i setting button image on navigation bar view controllers using following code in appdelegate:

    [[uibarbuttonitem appearance] setbackbuttonbackgroundimage:image forstate:uicontrolstatenormal barmetrics:uibarmetricsdefault]; 

now in 1 of view controllers pick newimage gallery , save it. want save newimage, 'image' of button gets replaced 'newimage'.

i tried following code in viewwillappear of each , every view controller

    [self.navigationitem.backbarbuttonitem setbackbuttonbackgroundimage:newimage forstate:uicontrolstatenormal barmetrics:uibarmetricsdefault]; 

and tried

 [self.navigationitem.backbarbuttonitem setimage:new]; 

this too. in vain. image gets changed when run app again , when code in appdelegate gets called.

plz help!

for set own image button need set custom appearance . , call in appdelegate.h file.

note: need set once in appdelegate.h , apply in whole project. don't need declare in each , every controller.

please check this.

   //in appdelegate.h file - (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions { [self customappearance]; //method declaration } 

and declare image image name in custom appearance. this,

-(void)customappearance { //int imagesize = 20; uiimage *myimage = [uiimage imagenamed:@"icon_back"]; //set backbutton imagename uiimage *backbuttonimage = [myimage imagewithrenderingmode:uiimagerenderingmodealwaysoriginal]; // use new backbuttomimage [[uinavigationbar appearance] setbackindicatorimage:backbuttonimage]; [[uinavigationbar appearance] setbackindicatortransitionmaskimage:backbuttonimage];   /*  uiimage *backbutton=[[uiimage imagenamed:@"icon_back"]resizableimagewithcapinsets:uiedgeinsetsmake(0, 0, 0, 0) resizingmode:uiimageresizingmodestretch];   //resizableimagewithcapinsets:uiedgeinsetsmake(0, 0, 0, 0) resizingmode:uiimageresizingmodestretch];   [[uibarbuttonitem appearance] setbackbuttonbackgroundimage:backbutton forstate:uicontrolstatenormal barmetrics:uibarmetricsdefault];*/ [[uibarbuttonitem appearance] setbackbuttontitlepositionadjustment:uioffsetmake(-400.f, 0)                                                      forbarmetrics:uibarmetricsdefault];  } 

and navigationbar button this.