ios - UIButton Image is not changed in Hightlight or Selected state -

i wrote following code of button ios8 app:

     uibutton *btnback = [uibutton buttonwithtype:uibuttontypecustom];     [btnback setframe:cgrectmake(40, 30, 30, 30)];     [btnback setbackgroundimage:[uiimage imagenamed:@"btn_close.png"]forstate:uicontrolstatenormal];     [btnback setbackgroundimage:[uiimage imagenamed:@"btn_close_on.png"] forstate:uicontrolstatehighlighted|uicontrolstateselected];     [btnback addtarget:self action:@selector(btnbackclick:) forcontrolevents:uicontroleventtouchupinside];     [self.view addsubview:btnback]; 

and method when click:

-(void) btnbackclick:(id)sender{ [self.navigationcontroller poptorootviewcontrolleranimated:yes]; } 

however, background of image not change when button being click. effect grayout.

if draw button on xib file, image change works charm.

anything wrong? please help.

uibutton *btnback = [uibutton buttonwithtype:uibuttontypecustom]; [btnback setframe:cgrectmake(40, 30, 30, 30)]; [btnback setbackgroundimage:[uiimage imagenamed:@"btn_close.png"]forstate:uicontrolstatenormal]; [btnback setbackgroundimage:[uiimage imagenamed:@"btn_close_on.png"] forstate:uicontrolstatehighlighted|uicontrolstateselected]; [btnback addtarget:self action:@selector(btnbackclick:) forcontrolevents:uicontroleventtouchupinside]; [btnback setselected:yes]; [self.view addsubview:btnback]; 

//**********updated*******

uibutton *btnback = [uibutton buttonwithtype:uibuttontypecustom]; [btnback setframe:cgrectmake(40, 30, 30, 30)]; [btnback setbackgroundimage:[uiimage imagenamed:@"btn_close.png"]forstate:uicontrolstatenormal]; [btnback setbackgroundimage:[uiimage imagenamed:@"btn_close_on.png"] forstate:uicontrolstatehighlighted]; [btnback setbackgroundimage:[uiimage imagenamed:@"btn_close_on.png"] forstate:uicontrolstateselected]; [btnback addtarget:self action:@selector(btnbackclick:) forcontrolevents:uicontroleventtouchupinside]; [self.view addsubview:btnback];  -(void)btnbackclick:(uibutton *)btn {     if ([btn isselected])     {         [btn setselected:no];     }     else         [btn setselected:yes]; }