Will enable support for customizing transitions using a transitionController.

• Add a settable replicaControllerDelegate API. Setting this property should assign the delegate to the director's private replicaController instance.

Blocked by #2, #3.

This transition should be a simple TransitionDirector instance.

Only one plan should be registered: the right view controller "shifting up" during presentation.

• Create an MDMSlideTransitionDirector class.
• Implement the slide transition using the CoreAnimation motion family.

This transition should support any direction of sliding when being presented.

We currently always treat every transition as an interactive transition. This is somewhat against the intended use of UIKit's transitioning APIs.

What we should be doing is acting as an interactive transition if there is some indication that the transition is, in fact, interactive. One signal we can use to start is whether any gesture recognizers associated with the transition are active.

Until we start working on interactive transitions support (Milestone 2) we may want to consider simplifying the transition controller logic to only implement the animated API variants.

Add a dependency to the runtime-objc repo's cocoapods file: https://github.com/material-motion/material-motion-runtime-objc

May be helpful to publish our own specs repo for development purposes.

The controller holds onto a reference of the transition but never releases it. It should release the transition instance when the transition completes.

The transition should provide a delegate that the controller can assign itself to in order to receive a "didFinish" event. The controller should nil out the transition instance when this event is received.

Spec: https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/interactions/transitions/platform/ios/TransitionController.html

Should lazily create an MDMTransitionController instance and assign it to the transitioningDelegate

They are not, currently. This means the transition controller has no way of knowing when the transition has completed. As a result, the activeTransition object is held for much longer than it needs to be.

Spec: https://material-motion.github.io/material-motion/starmap/specifications/interactions/transitions/TransitionWindow

Spec: https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/replicator_controller.html

As specific diffs:

• Create an empty MDMReplicaController class with barebones documentation.
• Create an empty MDMReplicaControllerDelegate protocol and corresponding delegate property on MDMReplicaController.
• Implement the createReplica API.
• Implement the disableReplicationForElement API.

https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/interactions/transitions/time_window.html

Spec: https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/transition_director.html

This breaks the overCurrentContext modal presentation style. Specifically, when we dismiss such a view controller we're left with a black screen.

Also make willPresentForeViewController an instance method that is called before setUp.

https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/interactions/transitions/Transition.html

Spec: https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/transition_director.html

This can be landed in multiple diffs:

• Land an empty MDMTransitionDirector interface with documentation.
• Define a setUp method that's designed to be subclassed (make this clear in the documentation of the method).
• Provide an initial direction API. Transitions can go either to the left or to the right.

Context:
http://codereview.cc/D1201#inline-4555
material-motion/tools#74

Should be capable of registering gesture recognizers that initiate an action when the gesture recognizer starts.

Example API signature:

typedef NS_ENUM(NSUInteger, MDMTransitionAction) {
  MDMTransitionActionPush,
  MDMTransitionActionPop,
  MDMTransitionActionPresent,
  MDMTransitionActionDismiss
};

- (void)whenGestureRecognizerBegins:(nonnull UIGestureRecognizer *)gestureRecognizer
                      performAction:(MDMTransitionAction)action;

When the gesture recognizer begins the action should be taken, initiating the creation of the relevant Director.

This is a private API and does not have a spec in the starmap because it is UIKit-specific.

• Created when a transition begins.
• Must conform to both UIViewControllerAnimatedTransitioning and UIViewControllerInteractiveTransitioning
• Must be initialized with an instance of a MDMTransitionDirector, the initial transition direction (to the left/to the right).

Might be able to make use of CF_SWIFT_NAME:

https://developer.apple.com/library/content/documentation/Swift/Conceptual/BuildingCocoaApps/InteractingWithCAPIs.html#//apple_ref/doc/uid/TP40014216-CH8-ID209

Goal is to be able to do TransitionWindowSegment.entire, TransitionWindowSegment.firstHalf, etc... as per the spec.

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented
                                                                  presentingController:(UIViewController *)presenting
                                                                      sourceController:(UIViewController *)source;

Must return an instance that conforms to UIViewControllerAnimatedTransitioning. This instance should be a separate bridging object that creates the scheduler and director instances and coordinates their overall execution.

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed;

Similar to the above, but requires a bit of shenanigans to infer the sourceViewController.

- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id<UIViewControllerAnimatedTransitioning>)animator;

If we're driving this transition, the interaction controller is always the animator instance we returned in the first method.

- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator;

If we're driving this transition, the interaction controller is always the animator instance we returned in the first method.

Spec: https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/transition_controller.html

This controller publicly conforms to UIViewControllerTransitioningDelegate.

Example use:

viewController.mdm_transitionController.directorClass = [PhotoDirector class];

Class prototype:

MDMTransitionController : NSObject <UIViewControllerTransitioningDelegate>

When mdm_transitionController is accessed, an instance of MDMTransitionController should lazily be created and then assigned to the view controller's transitioningDelegate (if one is not already set). This will allow us to hook in to the iOS view controller transitioning APIs.

Spec: https://material-motion.github.io/material-motion/starmap/specifications/plans/TransitionTween

https://material-motion.gitbooks.io/material-motion-starmap/content/specifications/interactions/transitions/TransitionDirector.html