WWDC 2013 Session笔记 - iOS7中的ViewController切换

//ContainerVC.m

[self addChildViewController:toVC];
[fromVC willMoveToParentViewController:nil];
[self.view addSubview:toVC.view];

__weak id weakSelf = self;
[self transitionFromViewController:fromVC
                  toViewController:toVC duration:0.3
                           options:UIViewAnimationOptionTransitionCrossDissolve
                        animations:^{}
                        completion:^(BOOL finished) {
    [fromVC.view removeFromSuperView];
    [fromVC removeFromParentViewController];
    [toVC didMoveToParentViewController:weakSelf];
}];

//ModalViewController.h

@class ModalViewController;
@protocol ModalViewControllerDelegate <NSObject>

-(void) modalViewControllerDidClickedDismissButton:(ModalViewController *)viewController;

@end

@interface ModalViewController : UIViewController
@property (nonatomic, weak) id<ModalViewControllerDelegate> delegate;
@end

//ModalViewController.m
- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor lightGrayColor];
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(80.0, 210.0, 160.0, 40.0);
    [button setTitle:@"Dismiss me" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

-(void) buttonClicked:(id)sender
{
    if (self.delegate && [self.delegate respondsToSelector:@selector(modalViewControllerDidClickedDismissButton:)]) {
        [self.delegate modalViewControllerDidClickedDismissButton:self];
    }
}

//MainViewController.m

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view.
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(80.0, 210.0, 160.0, 40.0);
    [button setTitle:@"Click me" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

-(void) buttonClicked:(id)sender
{
    ModalViewController *mvc =  [[ModalViewController alloc] init];
    mvc.delegate = self;
    [self presentViewController:mvc animated:YES completion:nil];
}

-(void)modalViewControllerDidClickedDismissButton:(ModalViewController *)viewController
{
    [self dismissViewControllerAnimated:YES completion:nil];
}

//BouncePresentAnimation.h
@interface BouncePresentAnimation : NSObject<UIViewControllerAnimatedTransitioning>

@end

//BouncePresentAnimation.m
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
    return 0.8f;
}

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
{
    // 1. Get controllers from transition context
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    // 2. Set init frame for toVC
    CGRect screenBounds = [[UIScreen mainScreen] bounds];
    CGRect finalFrame = [transitionContext finalFrameForViewController:toVC];
    toVC.view.frame = CGRectOffset(finalFrame, 0, screenBounds.size.height);
    
    // 3. Add toVC's view to containerView
    UIView *containerView = [transitionContext containerView];
    [containerView addSubview:toVC.view];
    
    // 4. Do animate now
    NSTimeInterval duration = [self transitionDuration:transitionContext];
    [UIView animateWithDuration:duration
                          delay:0.0
         usingSpringWithDamping:0.6
          initialSpringVelocity:0.0
                        options:UIViewAnimationOptionCurveLinear
                     animations:^{
                         toVC.view.frame = finalFrame;
                     } completion:^(BOOL finished) {
                         // 5. Tell context that we completed.
                         [transitionContext completeTransition:YES];
                     }];
}

@interface MainViewController ()<ModalViewControllerDelegate, UIViewControllerTransitioningDelegate>
@property (nonatomic, strong) BouncePresentAnimation *presentAnimation;
@end

@implementation MainViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
        _presentAnimation = [BouncePresentAnimation new];
    }
    return self;
}

-(void) buttonClicked:(id)sender
{
    //...
    mvc.transitioningDelegate = self;
    //...
}

- (id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    return self.presentAnimation;
}

//SwipeUpInteractiveTransition.h
@interface SwipeUpInteractiveTransition : UIPercentDrivenInteractiveTransition

@property (nonatomic, assign) BOOL interacting;

- (void)wireToViewController:(UIViewController*)viewController;

@end

//SwipeUpInteractiveTransition.m
@interface SwipeUpInteractiveTransition()
@property (nonatomic, assign) BOOL shouldComplete;
@property (nonatomic, strong) UIViewController *presentingVC;
@end

@implementation SwipeUpInteractiveTransition
-(void)wireToViewController:(UIViewController *)viewController
{
    self.presentingVC = viewController;
    [self prepareGestureRecognizerInView:viewController.view];
}

- (void)prepareGestureRecognizerInView:(UIView*)view {
    UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleGesture:)];
    [view addGestureRecognizer:gesture];
}

-(CGFloat)completionSpeed
{
    return 1 - self.percentComplete;
}

- (void)handleGesture:(UIPanGestureRecognizer *)gestureRecognizer {
    CGPoint translation = [gestureRecognizer translationInView:gestureRecognizer.view.superview];
    switch (gestureRecognizer.state) {
        case UIGestureRecognizerStateBegan:
            // 1. Mark the interacting flag. Used when supplying it in delegate.
            self.interacting = YES;
            [self.presentingVC dismissViewControllerAnimated:YES completion:nil];
            break;
        case UIGestureRecognizerStateChanged: {
            // 2. Calculate the percentage of guesture
            CGFloat fraction = translation.y / 400.0;
            //Limit it between 0 and 1
            fraction = fminf(fmaxf(fraction, 0.0), 1.0);
            self.shouldComplete = (fraction > 0.5);

            [self updateInteractiveTransition:fraction];
            break;
        }
        case UIGestureRecognizerStateEnded:
        case UIGestureRecognizerStateCancelled: {
            // 3. Gesture over. Check if the transition should happen or not
            self.interacting = NO;
            if (!self.shouldComplete || gestureRecognizer.state == UIGestureRecognizerStateCancelled) {
                [self cancelInteractiveTransition];
            } else {
                [self finishInteractiveTransition];
            }
            break;
        }
        default:
            break;
    }
}

@end

//MainViewController.m
@interface MainViewController ()<ModalViewControllerDelegate,UIViewControllerTransitioningDelegate>
//...
// 1. Add dismiss animation and transition controller
@property (nonatomic, strong) NormalDismissAnimation *dismissAnimation;
@property (nonatomic, strong) SwipeUpInteractiveTransition *transitionController;
@end

@implementation MainViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
 	//...
        _dismissAnimation = [NormalDismissAnimation new];
        _transitionController = [SwipeUpInteractiveTransition new];
	//...
}

-(void) buttonClicked:(id)sender
{
	//...
	// 2. Bind current VC to transition controller.
    [self.transitionController wireToViewController:mvc];
	//...
}

// 3. Implement the methods to supply proper objects.
-(id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    return self.dismissAnimation;
}

-(id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator {
    return self.transitionController.interacting ? self.transitionController : nil;
}