UINavigation左侧自定义返回箭头及距离左侧距离

自定义返回箭头

    UIImage *backImage = [[UIImage imageNamed:@"backicon.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    [self.navigationController.navigationBar setBackIndicatorImage:backImage];
    [self.navigationController.navigationBar setBackIndicatorTransitionMaskImage:backImage];

距离左侧距离

  UIBarButtonItem *leftButon = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"BackButton"] style:UIBarButtonItemStylePlain target:nil action:nil];  
      ```
      
      UIBarButtonItem *fixedButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];  
      
      fixedButton.width = -15;  
  
      self.navigationItem.leftBarButtonItems = @[fixedButton, leftButon];