总定义push，pop方向

-(void) setUpBackBut{

    

    UIButton *backBut=[[UIButtonalloc]init];

    

    [backBut setImage:[UIImageimageNamed:@"navgationbar_back_but"]forState:UIControlStateNormal];

    

    [backBut sizeToFit];

    

    [backBut addTarget:selfaction:@selector(backBUtClicked)forControlEvents:UIControlEventTouchUpInside];

    

    self.navigationItem.leftBarButtonItem=[[UIBarButtonItemalloc]initWithCustomView:backBut];

}

-(void) backBUtClicked{

    

    CATransition *anim=[CATransitionanimation];

    

    anim.type=kCATransitionPush;

    

    anim.subtype=kCATransitionFromRight;

    

    [self.navigationController.view.layeraddAnimation:anim forKey:nil];

    

    [self.navigationControllerpopViewControllerAnimated:YES];

    

}