UIImage *backButtonHomeImage = [[UIImage imageNamed:@"nav_back"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 30, 0, 0)];
    
    [[UIBarButtonItem appearance] setBackButtonBackgroundImage:backButtonHomeImage  forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
    
    
     //隱藏下級導航欄的backbutton title
    UIBarButtonItem *temporaryBarButtonItem = [[UIBarButtonItem alloc] init];
    
    temporaryBarButtonItem.title = @" ";
    
    self.navigationItem.backBarButtonItem = temporaryBarButtonItem;
 

或者使用左鍵代替返回鍵

    NSMutableArray * leftBarButtonItems = [[NSMutableArray alloc] initWithCapacity:0];
    
    UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
    
    [backButton setBackgroundImage:[UIImage imageNamed:@"nav_back"] forState:UIControlStateNormal];
    
    [backButton addTarget:self action:@selector(goBack) forControlEvents:UIControlEventTouchUpInside];
    
    backButton.frame = CGRectMake(0, 7, 30, 30);
    
    UIBarButtonItem *leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
    
    [leftBarButtonItems addObject:leftBarButtonItem];
    
    
    //佔位的button，減少返回鍵的觸控範圍===以下也可以不要
    UIButton *nullButton = [UIButton buttonWithType:UIButtonTypeCustom];
    
    UIBarButtonItem *nullBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:nullButton];
    
    [leftBarButtonItems addObject:nullBarButtonItem];
    
    [self.navigationItem setLeftBarButtonItems:leftBarButtonItems];