iOS Transition personnalisée UIDynamicBehavior


Exemple

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Cet exemple montre comment créer une transition de présentation personnalisée pilotée par un UIDynamicBehavior composite. Nous pouvons commencer par créer un contrôleur de vue de présentation qui présentera un modal.

Rapide

class PresentingViewController: UIViewController
{
    lazy var button: UIButton =
    {
        let button = UIButton()
        button.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive
            = true
        button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        button.setTitle("Present", for: .normal)
        button.setTextColor(UIColor.blue, for: .normal)
        
        return button
    }()
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        button.addTarget(self, action: #selector(self.didPressPresent), for: .touchUpInside)
    }
    
    func didPressPresent()
    {
        let modal = ModalViewController()
        modal.view.frame = CGRect(x: 0.0, y: 0.0, width: 200.0, height: 200.0)
        modal.modalPresentationStyle = .custom
        modal.transitioningDelegate = modal
        self.present(modal, animated: true)
    }
}

Objectif c

@interface PresentingViewController ()
@property (nonatomic, strong) UIButton *button;
@end

@implementation PresentingViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.button addTarget:self action:@selector(didPressPresent) forControlEvents:UIControlEventTouchUpInside];
}

- (void)didPressPresent
{
    ModalViewController *modal = [[ModalViewController alloc] init];
    modal.view.frame = CGRectMake(0.0, 0.0, 200.0, 200.0);
    modal.modalPresentationStyle = UIModalPresentationCustom;
    modal.transitioningDelegate = modal;
    [self presentViewController:modal animated:YES completion:nil];
}

- (UIButton *)button
{
    if (!_button)
    {
        _button = [[UIButton alloc] init];
        _button.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:_button];
        [_button.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
        [_button.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
        [_button setTitle:@"Present" forState:UIControlStateNormal];
        [_button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    }
    return _button;
}

@end

Lorsque vous appuyez sur le bouton actuel, nous créons un ModalViewController et définissons son style de présentation sur .custom et définissons son transitionDelegate sur lui-même. Cela nous permettra de proposer un animateur qui pilotera sa transition modale. Nous définissons également le cadre de la vue modal afin qu'il soit plus petit que le plein écran.

Regardons maintenant ModalViewController :

Rapide

class ModalViewController: UIViewController
{
    lazy var button: UIButton =
    {
        let button = UIButton()
        button.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive
         = true
        button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        button.setTitle("Dismiss", for: .normal)
        button.setTitleColor(.white, for: .normal)
        
        return button
    }()
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        button.addTarget(self, action: #selector(self.didPressDismiss), for: .touchUpInside)
        view.backgroundColor = .red
        view.layer.cornerRadius = 15.0
    }
    
    func didPressDismiss()
    {
        dismiss(animated: true)
    }
}

extension ModalViewController: UIViewControllerTransitioningDelegate
{
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?
    {
        return DropOutAnimator(duration: 1.5, isAppearing: true)
    }
    
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?
    {
        return DropOutAnimator(duration: 4.0, isAppearing: false)
    }
}

Objectif c

@interface ModalViewController () <UIViewControllerTransitioningDelegate>
@property (nonatomic, strong) UIButton *button;
@end

@implementation ModalViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.button addTarget:self action:@selector(didPressPresent) forControlEvents:UIControlEventTouchUpInside];
    self.view.backgroundColor = [UIColor redColor];
    self.view.layer.cornerRadius = 15.0f;
}

- (void)didPressPresent
{
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (UIButton *)button
{
    if (!_button)
    {
        _button = [[UIButton alloc] init];
        _button.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:_button];
        [_button.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
        [_button.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
        [_button setTitle:@"Dismiss" forState:UIControlStateNormal];
        [_button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    }
    return _button;
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    return [[DropOutAnimator alloc]initWithDuration: 1.5 appearing:YES];
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    return [[DropOutAnimator alloc] initWithDuration:4.0 appearing:NO];
}

@end

Ici, nous créons le contrôleur de vue qui est présenté. De plus, parce que ModalViewController est son propre transitioningDelegate il est également chargé de vendre un objet qui gérera son animation de transition. Pour nous, cela signifie transmettre une instance de notre sous-classe composite UIDynamicBehavior .

Notre animateur aura deux transitions différentes: une pour la présentation et une pour le rejet. Pour la présentation, la vue du contrôleur de vue de présentation apparaîtra d'en haut. Et pour le rejeter, la vue semblera balancer d’une corde puis tomber. Comme DropOutAnimator est conforme à UIViewControllerAnimatedTransitioning majeure partie de ce travail sera effectuée dans son implémentation de func animateTransition(using transitionContext: UIViewControllerContextTransitioning) .

Rapide

class DropOutAnimator: UIDynamicBehavior
{
    let duration: TimeInterval
    let isAppearing: Bool

    var transitionContext: UIViewControllerContextTransitioning?
    var hasElapsedTimeExceededDuration = false
    var finishTime: TimeInterval = 0.0
    var collisionBehavior: UICollisionBehavior?
    var attachmentBehavior: UIAttachmentBehavior?
    var animator: UIDynamicAnimator?

    init(duration: TimeInterval = 1.0,  isAppearing: Bool)
    {
        self.duration = duration
        self.isAppearing = isAppearing
        super.init()
    }
}

extension DropOutAnimator: UIViewControllerAnimatedTransitioning
{
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning)
    {
        // Get relevant views and view controllers from transitionContext
        guard let fromVC = transitionContext.viewController(forKey: .from),
              let toVC = transitionContext.viewController(forKey: .to),
              let fromView = fromVC.view,
              let toView = toVC.view else { return }
    
        let containerView = transitionContext.containerView
        let duration = self.transitionDuration(using: transitionContext)
    
        // Hold refrence to transitionContext to notify it of completion
        self.transitionContext = transitionContext
    
        // Create dynamic animator
        let animator = UIDynamicAnimator(referenceView: containerView)
        animator.delegate = self
        self.animator = animator
    
        // Presenting Animation
        if self.isAppearing
        {
            fromView.isUserInteractionEnabled = false
        
            // Position toView  just off-screen
            let fromViewInitialFrame = transitionContext.initialFrame(for: fromVC)
            var toViewInitialFrame = toView.frame
            toViewInitialFrame.origin.y -= toViewInitialFrame.height
            toViewInitialFrame.origin.x = fromViewInitialFrame.width * 0.5 - toViewInitialFrame.width * 0.5
            toView.frame = toViewInitialFrame
        
            containerView.addSubview(toView)
        
            // Prevent rotation and adjust bounce
            let bodyBehavior = UIDynamicItemBehavior(items: [toView])
            bodyBehavior.elasticity = 0.7
            bodyBehavior.allowsRotation = false
        
            // Add gravity at exaggerated magnitude so animation doesn't seem slow
            let gravityBehavior = UIGravityBehavior(items: [toView])
            gravityBehavior.magnitude = 10.0
        
            // Set collision bounds to include off-screen view and have collision in center 
            // where our final view should come to rest
            let collisionBehavior = UICollisionBehavior(items: [toView])
            let insets = UIEdgeInsets(top: toViewInitialFrame.minY, left: 0.0, bottom: fromViewInitialFrame.height * 0.5 - toViewInitialFrame.height * 0.5, right: 0.0)
            collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: insets)
            self.collisionBehavior = collisionBehavior
        
            // Keep track of finish time in case we need to end the animator befor the animator pauses
            self.finishTime = duration + (self.animator?.elapsedTime ?? 0.0)
        
            // Closure that is called after every "tick" of the animator
            // Check if we exceed duration
            self.action =
            { [weak self] in
                guard let strongSelf = self,
                  (strongSelf.animator?.elapsedTime ?? 0.0) >= strongSelf.finishTime else { return }
                strongSelf.hasElapsedTimeExceededDuration = true
                strongSelf.animator?.removeBehavior(strongSelf)
            }
        
            // `DropOutAnimator` is a composit behavior, so add child behaviors to self
            self.addChildBehavior(collisionBehavior)
            self.addChildBehavior(bodyBehavior)
            self.addChildBehavior(gravityBehavior)
        
            // Add self to dynamic animator
            self.animator?.addBehavior(self)
        }
        // Dismissing Animation
        else
        {
            // Create allow rotation and have a elastic item
            let bodyBehavior = UIDynamicItemBehavior(items: [fromView])
            bodyBehavior.elasticity = 0.8
            bodyBehavior.angularResistance = 5.0
            bodyBehavior.allowsRotation = true
        
            // Create gravity with exaggerated magnitude
            let gravityBehavior = UIGravityBehavior(items: [fromView])
            gravityBehavior.magnitude = 10.0
        
            // Collision boundary is set to have a floor just below the bottom of the screen
            let collisionBehavior = UICollisionBehavior(items: [fromView])
            let insets = UIEdgeInsets(top: 0.0, left: -1000, bottom: -225, right: -1000)
            collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: insets)
            self.collisionBehavior = collisionBehavior
        
            // Attachment behavior so view will have effect of hanging from a rope
            let offset = UIOffset(horizontal: 70.0, vertical: fromView.bounds.height * 0.5)
            var anchorPoint = CGPoint(x: fromView.bounds.maxX - 40.0, y: fromView.bounds.minY)
            anchorPoint = containerView.convert(anchorPoint, from: fromView)
            let attachmentBehavior = UIAttachmentBehavior(item: fromView, offsetFromCenter: offset, attachedToAnchor: anchorPoint)
            attachmentBehavior.frequency = 3.0
            attachmentBehavior.damping = 3.0
            self.attachmentBehavior = attachmentBehavior
        
            // `DropOutAnimator` is a composit behavior, so add child behaviors to self
            self.addChildBehavior(collisionBehavior)
            self.addChildBehavior(bodyBehavior)
            self.addChildBehavior(gravityBehavior)
            self.addChildBehavior(attachmentBehavior)
        
            // Add self to dynamic animator
            self.animator?.addBehavior(self)
        
            // Animation has two parts part one is hanging from rope. 
            // Part two is bouncying off-screen
            // Divide duration in two
            self.finishTime = (2.0 / 3.0) * duration + (self.animator?.elapsedTime ?? 0.0)
        
             // After every "tick" of animator check if past time limit
            self.action =
            { [weak self] in
                guard let strongSelf = self,
                  (strongSelf.animator?.elapsedTime ?? 0.0) >= strongSelf.finishTime else { return }
                strongSelf.hasElapsedTimeExceededDuration = true
                strongSelf.animator?.removeBehavior(strongSelf)
            }
        }
    
    }

    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval
    {
        // Return the duration of the animation
        return self.duration
    }
}

extension DropOutAnimator: UIDynamicAnimatorDelegate
{
    func dynamicAnimatorDidPause(_ animator: UIDynamicAnimator)
    {
      // Animator has reached stasis
      if self.isAppearing
      {
            // Check if we are out of time
            if self.hasElapsedTimeExceededDuration
            {
                // Move to final positions
                let toView = self.transitionContext?.viewController(forKey: .to)?.view
                let containerView = self.transitionContext?.containerView
                toView?.center = containerView?.center ?? .zero
                self.hasElapsedTimeExceededDuration = false
            }
            
            // Clean up and call completion
            self.transitionContext?.completeTransition(!(self.transitionContext?.transitionWasCancelled ?? false))
            self.childBehaviors.forEach { self.removeChildBehavior($0) }
            animator.removeAllBehaviors()
            self.transitionContext = nil
    }
    else
    {
        if let attachmentBehavior = self.attachmentBehavior
        {
            // If we have an attachment, we are at the end of part one and start part two.
            self.removeChildBehavior(attachmentBehavior)
            self.attachmentBehavior = nil
            animator.addBehavior(self)
            let duration = self.transitionDuration(using: self.transitionContext)
            self.finishTime = 1.0 / 3.0 * duration + animator.elapsedTime
        }
        else
        {
            // Clean up and call completion
            let fromView = self.transitionContext?.viewController(forKey: .from)?.view
            let toView = self.transitionContext?.viewController(forKey: .to)?.view
            fromView?.removeFromSuperview()
            toView?.isUserInteractionEnabled = true
            self.transitionContext?.completeTransition(!(self.transitionContext?.transitionWasCancelled ?? false))
            self.childBehaviors.forEach { self.removeChildBehavior($0) }
            animator.removeAllBehaviors()
            self.transitionContext = nil
        }
    }
}
}

Objectif c

@interface ObjcDropOutAnimator() <UIDynamicAnimatorDelegate, UIViewControllerAnimatedTransitioning>
@property (nonatomic, strong) id<UIViewControllerContextTransitioning> transitionContext;
@property (nonatomic, strong) UIDynamicAnimator *animator;
@property (nonatomic, assign) NSTimeInterval finishTime;
@property (nonatomic, assign) BOOL elapsedTimeExceededDuration;
@property (nonatomic, assign, getter=isAppearing) BOOL appearing;
@property (nonatomic, assign) NSTimeInterval duration;
@property (nonatomic, strong) UIAttachmentBehavior *attachBehavior;
@property (nonatomic, strong) UICollisionBehavior * collisionBehavior;

@end

@implementation ObjcDropOutAnimator

- (instancetype)initWithDuration:(NSTimeInterval)duration appearing:(BOOL)appearing
{
    self = [super init];
    if (self)
    {
        _duration = duration;
        _appearing = appearing;
    }
    return self;
}

- (void) animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    // Get relevant views and view controllers from transitionContext
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *fromView = fromVC.view;
    UIView *toView = toVC.view;
    
    UIView *containerView = transitionContext.containerView;
    NSTimeInterval duration = [self transitionDuration:transitionContext];
    
    // Hold refrence to transitionContext to notify it of completion
    self.transitionContext = transitionContext;
    
    // Create dynamic animator
    UIDynamicAnimator *animator = [[UIDynamicAnimator alloc]initWithReferenceView:containerView];
    animator.delegate = self;
    self.animator = animator;
    
    // Presenting Animation
    if (self.isAppearing)
    {
        fromView.userInteractionEnabled = NO;
        
        // Position toView  just above screen
        CGRect fromViewInitialFrame = [transitionContext initialFrameForViewController:fromVC];
        CGRect toViewInitialFrame = toView.frame;
        toViewInitialFrame.origin.y -= CGRectGetHeight(toViewInitialFrame);
        toViewInitialFrame.origin.x = CGRectGetWidth(fromViewInitialFrame) * 0.5 - CGRectGetWidth(toViewInitialFrame) * 0.5;
        toView.frame = toViewInitialFrame;
        
        [containerView addSubview:toView];
        
        // Prevent rotation and adjust bounce
        UIDynamicItemBehavior *bodyBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[toView]];
        bodyBehavior.elasticity = 0.7;
        bodyBehavior.allowsRotation = NO;
        
        // Add gravity at exaggerated magnitude so animation doesn't seem slow
        UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc]initWithItems:@[toView]];
        gravityBehavior.magnitude = 10.0f;
        
        // Set collision bounds to include off-screen view and have collision floor in center
        // where our final view should come to rest
        UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc]initWithItems:@[toView]];
        UIEdgeInsets insets = UIEdgeInsetsMake(CGRectGetMinY(toViewInitialFrame), 0.0, CGRectGetHeight(fromViewInitialFrame) * 0.5 - CGRectGetHeight(toViewInitialFrame) * 0.5, 0.0);
        [collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:insets];
        self.collisionBehavior = collisionBehavior;
        
        // Keep track of finish time in case we need to end the animator befor the animator pauses
        self.finishTime = duration + self.animator.elapsedTime;
        
        // Closure that is called after every "tick" of the animator
        // Check if we exceed duration
        __weak ObjcDropOutAnimator *weakSelf = self;
        self.action = ^{
            __strong ObjcDropOutAnimator *strongSelf = weakSelf;
            if (strongSelf)
            {
                if (strongSelf.animator.elapsedTime >= strongSelf.finishTime)
                {
                    strongSelf.elapsedTimeExceededDuration = YES;
                    [strongSelf.animator removeBehavior:strongSelf];
                }
            }
        };
        
        // `DropOutAnimator` is a composit behavior, so add child behaviors to self
        [self addChildBehavior:collisionBehavior];
        [self addChildBehavior:bodyBehavior];
        [self addChildBehavior:gravityBehavior];
        
        // Add self to dynamic animator
        [self.animator addBehavior:self];
    }
    // Dismissing Animation
    else
    {
        // Allow rotation and have a elastic item
        UIDynamicItemBehavior *bodyBehavior = [[UIDynamicItemBehavior alloc] initWithItems:@[fromView]];
        bodyBehavior.elasticity = 0.8;
        bodyBehavior.angularResistance = 5.0;
        bodyBehavior.allowsRotation = YES;
        
        // Create gravity with exaggerated magnitude
        UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc] initWithItems:@[fromView]];
        gravityBehavior.magnitude = 10.0f;
        
        // Collision boundary is set to have a floor just below the bottom of the screen
        UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc] initWithItems:@[fromView]];
        UIEdgeInsets insets = UIEdgeInsetsMake(0, -1000, -225, -1000);
        [collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:insets];
        self.collisionBehavior = collisionBehavior;
        
        // Attachment behavior so view will have effect of hanging from a rope
        UIOffset offset = UIOffsetMake(70, -(CGRectGetHeight(fromView.bounds) / 2.0));
        
        CGPoint anchorPoint = CGPointMake(CGRectGetMaxX(fromView.bounds) - 40,
                                          CGRectGetMinY(fromView.bounds));
        anchorPoint = [containerView convertPoint:anchorPoint fromView:fromView];
        UIAttachmentBehavior *attachBehavior = [[UIAttachmentBehavior alloc] initWithItem:fromView offsetFromCenter:offset attachedToAnchor:anchorPoint];
        attachBehavior.frequency = 3.0;
        attachBehavior.damping = 0.3;
        attachBehavior.length = 40;
        self.attachBehavior = attachBehavior;
        
        // `DropOutAnimator` is a composit behavior, so add child behaviors to self
        [self addChildBehavior:collisionBehavior];
        [self addChildBehavior:bodyBehavior];
        [self addChildBehavior:gravityBehavior];
        [self addChildBehavior:attachBehavior];
        
        // Add self to dynamic animator
        [self.animator addBehavior:self];
        
        // Animation has two parts part one is hanging from rope.
        // Part two is bouncying off-screen
        // Divide duration in two
        self.finishTime = (2./3.) * duration + [self.animator elapsedTime];
        
        // After every "tick" of animator check if past time limit
        __weak ObjcDropOutAnimator *weakSelf = self;
        self.action = ^{
            __strong ObjcDropOutAnimator *strongSelf = weakSelf;
            if (strongSelf)
            {
                if ([strongSelf.animator elapsedTime] >= strongSelf.finishTime)
                {
                    strongSelf.elapsedTimeExceededDuration = YES;
                    [strongSelf.animator removeBehavior:strongSelf];
                }
            }
        };
    }
}

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return self.duration;
}

- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator
{
    // Animator has reached stasis
    if (self.isAppearing)
    {
        // Check if we are out of time
        if (self.elapsedTimeExceededDuration)
        {
            // Move to final positions
            UIView *toView = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
            UIView *containerView = [self.transitionContext containerView];
            toView.center = containerView.center;
            self.elapsedTimeExceededDuration = NO;
        }
        
        // Clean up and call completion
        [self.transitionContext completeTransition:![self.transitionContext transitionWasCancelled]];
        for (UIDynamicBehavior *behavior in self.childBehaviors)
        {
            [self removeChildBehavior:behavior];
        }
        [animator removeAllBehaviors];
        self.transitionContext = nil;
    }
    // Dismissing
    else
    {
        if (self.attachBehavior)
        {
            // If we have an attachment, we are at the end of part one and start part two.
            [self removeChildBehavior:self.attachBehavior];
            self.attachBehavior = nil;
            [animator addBehavior:self];
            NSTimeInterval duration = [self transitionDuration:self.transitionContext];
            self.finishTime = 1./3. * duration + [animator elapsedTime];
        }
        else
        {
            // Clean up and call completion
            UIView *fromView = [self.transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey].view;
            UIView *toView = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
            [fromView removeFromSuperview];
            toView.userInteractionEnabled = YES;
            
            [self.transitionContext completeTransition:![self.transitionContext transitionWasCancelled]];
            for (UIDynamicBehavior *behavior in self.childBehaviors)
            {
                [self removeChildBehavior:behavior];
            }
            [animator removeAllBehaviors];
            self.transitionContext = nil;
        }
    }
}

En tant que comportement composite, DropOutAnimator peut combiner différents comportements pour effectuer ses animations de présentation et de rejet. DropOutAnimator montre également comment utiliser le bloc d' action d'un comportement pour inspecter les emplacements de ses éléments, ainsi que le temps écoulé depuis une technique pouvant être utilisée pour supprimer les vues déplacées ou tronquer les animations qui n'ont pas encore atteint la stase.

Pour plus d'informations Session 2013 de la WWDC "Techniques avancées avec UIKit Dynamics" ainsi que SOLPresentingFun