3

I am completely new to iOS development and still have not managed how to accomplish such an easy task.

I have a raw xCode 4.4.1 "Single View Application" project.

I want to have, say, four screens, each having buttons for switching to other views.

Screens are not set up in a hierarchy: for example, I want to be able to switch to screen 2 or screen 3 from screen 1, to screen 4 from screen 2, and so on. On application run - the first screen is shown, but its status is not "root" or "main" - it is just a common screen among others.

My conditions are:

  1. I have just default main storyboard file (xib solutions are not fine).
  2. I don't want to rely on using Navigation controllers or similar pre-structured things.

It seems to me, that I need to somehow setup Container controller with child controllers as they are described in Session 102 from WWDC 2011, but I don't understand how to write up the code properly, so it will not conflict with main Storyboard (I have two failed attempts to use xib-based solutions from other similar topics here on SO).

I would highly appreciate a complete working example, because of my experience does not yet allow me to rely on partial hints, though they will be fine too.

A solution that will do this programmatically (not using xCode UI features like dragging) is preferred.

Thanks!

UPDATE: When switching, I don't want to instantiate new screens each time, but re-use existing ones, if they already exist.

UPDATE 2: My use case, simplified for this issue:

I have a registration screen, with corresponding modal screens to handle all common login/logout/etc situations. And I have main screen of my app, which becomes the "main" app screen after login/registration procedure is finished. I don't want to make registration screen/controller to be modal for the main screen, because the main screen pretty much depends on user-specific information, so I would like to have these screens not organized in hierarchy in any way. I think about having the following flow for this simplified situation:

1) User is not yet logged in - registration screen is presented. Later, after reg. procedure is done - switch (this is a key point I am not aware about, that is why this issue) to "main" screen.

2) User is logged in and is recognized by app - "main" screen is presented.

Having registration and "main" screens like I described excludes (or what?) the situation of having "Tab controller" functionality in "Tabbed application" template as is, because in my case I want to have tab bar completely disabled - what I need is not a nav. & nav bar functionality, but just the way to perform transition beetween reg. and "main" screens - this is what I mean "by hands" in my question.

FINAL UPDATE:

After experimenting with Tab Bar Controller, for this use-case I've ended up using Navigation Controller with navigation bar disabled (I didn't find analogous one in Tab bar controller) and managing the switching of screens by performSegueWithIdentifier method as well as switching them by manipulating viewControllers navigation stack "by hands".

Thank you all for answers!

Improve this question
6
  • 1
    The structure you are describing sounds like how a tab bar controller works. What's wrong with it? Commented Aug 11, 2012 at 11:04
  • 1) I think, it is ok with it, if it is possible to completely disable navigation tab bar and move navigation code to the buttons inside my views and trigger view switching from there. I can't understand well what's going on in xCode sample "Tabbed application" to achieve my goal. 2) For learning purposes I want to know how this could be done "by hands" - I suspect, that it should not be a difficult task to solve. Commented Aug 11, 2012 at 11:46
  • Could you provide a use case? Your question actually covers a lot of ground, and there are already several viable solutions in the current API. Do you want multiple view controllers on the screen at the same time, or you want to have your own navigation-type controller??? Commented Aug 12, 2012 at 7:28
  • For a beginner, I don't think re-implementing a tab bar is a great project. Understanding how a tab bar controller works would be a better idea. What don't you like / understand about them? It's a pretty simple control. Commented Aug 12, 2012 at 7:45
  • In fact, the direct answer to your questions title is to use a tab bar controller. Commented Aug 12, 2012 at 7:47

2 Answers 2

Reset to default
2

Probably the easiest thing to do is use segues in the storyboard.

right-click-drag from your main view controller to each of the others. It will ask what type of segue to create, and choose modal.

Then, make sure you give each of the segues a unique identifier string in the identifier property.

Now, from code, anytime you want one of those view controllers to become active, you call

[self performSegueWithIdentifier:@"Foo Segue" sender:(id)sender];

The sender object above can be anything you want, usually some information you want to pass o the view controller that is getting ready to be displayed.

Now, just before a segue is shown, whether programmatically or directly from storyboard defined interaction, the prepareForSegue method is called. So, you would then do something like this, again in the code for the "main" view controller.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // You have access to the view controller that is getting ready to be
    // displayed, as well as the identifier, so you can set values or whatever
    // before the view controller is presented.
    if ([segue.identifier isEqualToString:@"Foo Segue"]) {
        FooViewController *vc = segue.destinationViewController;
        // The view controller is completely instantiated, and you can do any
        // setup work, like setting property values on the view controller
        // to give it its model, or whatever else you want to do.
    }
}

Now, you need some way to know when that controller is done. This can be done several ways. The presented view controller can dismiss itself, or can use a delegate or notification to tell the presenting view controller that is is done and should be dismissed.

In your case, it may well be fine to let the presented VC dismiss itself. So, just call

[self dismissViewControllerAnimated:YES completion:nil];

If you do not want to use segues, you can will have to load your VCs directly from the storyboard (or give them their own nib). To instantiate from the storyboard, you have to give the view controllers you want to instantiate their own identifier tag (again look in the property pane and set the property on the VC).

Then you can do this (assuming the VC that houses this code is in the same storyboard as the VC it is trying to instantiate)...

FooViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:@"FooViewController"];

Then, you actually present that controller with...

[self presentViewController:vc animated:YES completion:nil];

Of course, there are several other ways to do this, and there are a few pros/cons on each approach. I suggest you play with it and read the associated documentation so you can make an educated decision about which method to use.

In any event, the above should give you a somewhat easy path toward your goal.

Improve this answer
Sign up to request clarification or add additional context in comments.

4 Comments

This isn't necessarily the best way to do it - depending how the switching is implemented you could end up creating new instances of the view controllers every time instead of switching between existing instances.
True. There are other issues as well. However, it does provide a general overview and small cost-of-entry starting point for learning. This isn't the place for a complete tutorial. However, if you have a better way of giving a high level starting point, and addressing all the details, please do so.
I'm not sure there is one - like you say, it would have to be a whole tutorial!
I did my best to stay away from custom controller containers, but as you mentioned in your great answer, that's probably the right (and advanced) way to do it if tab-bar is not going to work.
2

The short answer to your question is to use a tab bar controller. This is an outwardly simple control that actually manages a lot of complexity, and re-implementing it is not a good idea for a beginner, or for the users of your application, who will be used to how a tab bar controller works.

The tab bar controller has a property (viewControllers) which you can populate in the storyboard by control-dragging to your other scenes. The tab bar controller interrogates each of these view controllers to build the tab bar (names and images, the appropriate number of items, a "More" controller if there are too many to fit on the bar) and handles switching between each of them, altering the size of the contained views and the tab bar to handle rotation events. The tab bar controller's view therefore contains two subviews - one to hold the tab bar, and one to hold the view of the currently displayed view controller.

You'd need to duplicate all of that functionality yourself, which is pretty complicated for a beginner, and certainly outside the scope of a Stack Overflow answer. The fact that you'd be duplicating existing functionality should also be a red flag as to if you really ought to be working that way.

Implementing a tab bar-type controller yourself isn't supported by storyboards either, since the key part (the "Relationship - View Controllers") is not available for custom container view controllers. You'd therefore have to set up your UI in code and manually instantiate the view controllers to set up the relationship, which may well clash with your main storyboard - though your sentence about preferring to do this programmatically sort of clashes with the storyboard request in the question title, so I'm a little confused by that.

A brief overview of how you could implement this if you still wanted to:

  • Create a custom UIViewController
  • Add a viewControllers property, and some sort of control to handle the switching, probably a segmented control
  • When the viewControllers property is set, get the title to set as the title of one of your segmented control segments. Add the view of the first item in the array as a subview of your main view (with the appropriate frame so it doesn't cover your segmented control) and add it as a child view controller using [self addChildViewController:vc] and [vc didMoveToParentViewController:self])
  • When the segmented control's value changes, remove the current view controller's view from the view hierarchy (removeFromSuperview) and the view controller hierarchy (removeFromParentViewController), and add in the newly selected view controller's view using the code above.
Improve this answer

1 Comment

Thanks for detailed answer. I am more than enough convinced to use Tab bar controller. Please see my answer on your question in direct comments to my original question.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.