Quickies for UINavigationController

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General

• Add a cancel button to a navigation bar. [permalink]
  In your -viewDidLoad :

      UIBarButtonItem *cancelButton =
  	[[UIBarButtonItem alloc] initWithTitle: @"Cancel"
                                   style: UIBarButtonItemStylePlain
                                   target: self
                                   action: @selector(cancel:)];
      self.navigationItem.rightBarButtonItem = cancelButton;
      [cancelButton release];

• Adding a plus button to a navigation bar [permalink]
  

      UIBarButtonItem *addButton  =
          [[UIBarButtonItem alloc]
              initWithBarButtonSystemItem: UIBarButtonSystemItemAdd
              target: self
              action: @selector(addNewSegment)];
      self.navigationItem.rightBarButtonItem = addButton;
      [addButton release];
  

• Adding an info button to the nav bar [permalink]
  

  UIButton *button = [UIButton buttonWithType: UIButtonTypeInfoLight];
  [button addTarget: self
          action: @selector(about:)
          forControlEvents: UIControlEventTouchUpInside];
  
  UIBarButtonItem *infoItem =
      [[UIBarButtonItem alloc] initWithCustomView: button];
  
  ... make any other button items you want
  
  NSArray *rightButtonItems = @[ spacer, infoItem, widerSpace, someOtherItem ];
  _viewController.navigationItem.rightBarButtonItems = rightButtonItems;
  

• Hide the navigation bar's "Back" button. [permalink]
  

      self.navigationItem.hidesBackButton = YES;

• Hiding the navigation bar [permalink]
  Say you had a main screen that doesn't need to show the navigation bar. When you "Back" from another view controller your delegate will get called. You can decide then whether to turn off the nav bar.

  - (void) navigationController: (UINavigationController *) navigationController
         willShowViewController: (UIViewController *) viewController
                       animated: (BOOL) animated {
      if (viewController == _menuController) {
          [_navigationController setNavigationBarHidden: YES
                                 animated: YES];
      }
  } // willShowViewController
  

• Popping the current view controller [permalink]
  Say the user selected a row in a tableview, and now we're done with this view controller:

  - (void)tableView: (UITableView *) tableView
      didSelectRowAtIndexPath: (NSIndexPath *) indexPath {
  
      // might want someone to know what the user picked.
      [_delegate kindChooser: self
                 choseWorkoutType: mapRowToWorkoutType(indexPath.row)];
  
      // pop ourselves off the stack.
      [self.navigationController popViewControllerAnimated: YES];
  
  } // didSelectRowAtIndexPath
  

• Pushing a new view controller onto the stack. [permalink]
  Moving to another view controller from the current one.

      GRChooseRideKindViewController *chooseKind =
          [[GRChooseRideKindViewController alloc] init];
  
      [self.navigationController pushViewController: chooseKind
           animated: YES];
  
      [chooseKind release];

Swift

• Show navigation bar on push [permalink]
  Say you have a pretty main menu that's in a nav controller, and tapping on buttons take you to pushed view controllers. The pushed VCs need the navbar so they can go Back, but the pretty main menu doesn't need the navbar. Swift 3

  class PrettyMainMenuViewController: UIViewController {
      override func viewDidLoad() {
          super.viewDidLoad()
          self.navigationController?.delegate = self
      }
  }
  
  extension PrettyMainMenuViewController: UINavigationControllerDelegate {
      func navigationController(_ navigationController: UINavigationController, 
                                willShow viewController: UIViewController,
                                animated: Bool) {
          if viewController === self {
              navigationController.setNavigationBarHidden(true, animated: true)
          } else {
              navigationController.setNavigationBarHidden(false, animated: true)
          }
      }
  }
  

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