TigerCoding TigerCoding - 5 months ago 32
iOS Question

Animate change of view controllers without using navigation controller stack, subviews or modal controllers?

NavigationControllers have ViewController stacks to manage, and limited animation transitions.

Adding a view controller as a sub-view to an existing view controller requires passing events to the sub-view controller, which is a pain to manage, loaded with little annoyances and in general feels like a bad hack when implementing (Apple also recommends against doing this).

Presenting a modal view controller again places a view controller on top of another, and while it doesn't have the event passing problems described above, it doesn't really 'swap' the view controller, it stacks it.

Storyboards are limited to iOS 5, and are almost ideal, but cannot be used in all projects.

Can someone present a SOLID CODE EXAMPLE on a way to change view controllers without the above limitations and allows for animated transitions between them?

A close example, but no animation:
How to use multiple iOS custom view controllers without a navigation controller

Edit: Nav Controller use is fine, but there needs to be animated transition styles (not simply the slide effects) the view controller being shown needs to be swapped completely (not stacked). If the second view controller must remove another view controller from the stack, then it's not encapsulated enough.

Edit 2: iOS 4 should be the base OS for this question, I should have clarified that when mentioning storyboards (above).

Answer

EDIT: New answer that works in any orientation. The original answer only works when the interface is in portrait orientation. This is b/c view transition animations that replace a view w/ a different view must occur with views at least a level below the first view added to the window (e.g. window.rootViewController.view.anotherView).

I've implemented a simple container class I called TransitionController. You can find it at https://gist.github.com/1394947.

As an aside, I prefer the implementation in a separate class b/c it's easier to reuse. If you don't want that, you could simply implement the same logic directly in your app delegate eliminating the need for the TransitionController class. The logic you'd need would be the same however.

Use it as follows:

In your app delegate

// add a property for the TransitionController

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    MyViewController *vc = [[MyViewContoller alloc] init...];
    self.transitionController = [[TransitionController alloc] initWithViewController:vc];
    self.window.rootViewController = self.transitionController;
    [self.window makeKeyAndVisible];
    return YES;
}

To transition to a new view controller from any view controller

- (IBAction)flipToView
{
    anotherViewController *vc = [[AnotherViewController alloc] init...];
    MyAppDelegate *appDelegate = [UIApplication sharedApplication].delegate;
    [appDelegate.transitionController transitionToViewController:vc withOptions:UIViewAnimationOptionTransitionFlipFromRight];
}

EDIT: Original Answer below - only works for portait orientation

I made the following assumptions for this example:

  1. You have a view controller assigned as the rootViewController of your window

  2. When you switch to a new view you want to replace the current viewController with the viewController owning the new view. At any time, only the current viewController is alive (e.g. alloc'ed).

The code can be easily modified to work differently, the key point is the animated transition and the single view controller. Make sure you don't retain a view controller anywhere outside of assigning it to window.rootViewController.

Code to animate transition in app delegate

- (void)transitionToViewController:(UIViewController *)viewController
                    withTransition:(UIViewAnimationOptions)transition
{
    [UIView transitionFromView:self.window.rootViewController.view
                        toView:viewController.view
                      duration:0.65f
                       options:transition
                    completion:^(BOOL finished){
                        self.window.rootViewController = viewController;
                    }];
}

Example use in a view controller

- (IBAction)flipToNextView
{
    AnotherViewController *anotherVC = [[AnotherVC alloc] init...];
    MyAppDelegate *appDelegate = (MyAppDelegate *)[UIApplication sharedApplication].delegate;
    [appDelegate transitionToViewController:anotherVC
                             withTransition:UIViewAnimationOptionTransitionFlipFromRight];
}
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