How do I set a custom view back button - ios

Question

In View Controller A, in viewDid Load I have this:
UIImage * backButtonImage = [UIImage imageNamed: #"bar-arrow"];
UIBarButtonItem* b = [[UIBarButtonItem alloc] initWithImage:backButtonImage style:UIBarButtonItemStylePlain target:nil action:nil];
self.navigationItem.backBarButtonItem = b;
Still In the next view controller's nav. bar I get this:
In other words - the original back arrow of IOS7 still shows. cannot get rid of it!!

Answer 1

Generally hide default back button from NativationBar:
[self.navigationItem setHidesBackButton:YES animated:YES];
[self.navigationItem setHidesBackButton:YES];
and do following code:
UIButton *BackButton = [UIButton buttonWithType:UIButtonTypeCustom];
[BackButton setImage:[UIImage imageNamed:#"bar-arrow"] forState:UIControlStateNormal];
[BackButton addTarget:self action:#selector(prevButtonAction)forControlEvents:UIControlEventTouchUpInside];
[BackButton setFrame:CGRectMake(0, 0, 12, 20)];// set as par your need
UIBarButtonItem *barButton = [[UIBarButtonItem alloc] initWithCustomView:BackButton];
self.navigationItem.leftBarButtonItem = barButton;
-(void)prevButtonAction
{
[self.navigationController popViewControllerAnimated:YES];
}

Answer 2

If you want to keep the back button functionality but just change the chevron image (and if you are targeting only iOS 7.0 and above), you can change the image like so:
- (void)viewDidLoad
{
[super viewDidLoad];
self.navigationController.navigationBar.backIndicatorImage = [UIImage imageNamed:#"bar-arrow"];
self.navigationController.navigationBar.backIndicatorTransitionMaskImage = [UIImage imageNamed:#"bar-arrow-transition-mask"];
}
Or if you were to subclass a UINavigationController, which I would suggest:
- (void)viewDidLoad
{
[super viewDidLoad];
self.navigationBar.backIndicatorImage = [UIImage imageNamed:#"bar-arrow"];
self.navigationBar.backIndicatorTransitionMaskImage = [UIImage imageNamed:#"bar-arrow-transition-mask"];
}
... where the "bar-arrow-transition-mask" image is an image representing the visibility of the other image, "bar-arrow". In this mask image, pixels with an alpha of zero will completely hide the moving title during transitions, while pixels with an alpha of one will completely show the moving title.
While this will require you to make a new image, it should be very quick and easy to make, and this solution preserves all navigation bar functionality without messing with the leftBarButtonItem or leftBarButtonItems and adding in manual calls to popViewControllerAnimated:.