UIDynamicBehavior 驅動自定義轉換
https://i.stack.imgur.com/VAeNo.gif
此示例顯示如何建立由複合 UIDynamicBehavior 驅動的自定義簡報轉換。我們可以從建立呈現檢視控制器開始，該控制器將呈現模態。
迅速
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)
}
}
Objective-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
當點選當前按鈕時，我們建立一個 ModalViewController 並將其演示樣式設定為 .custom 並將其 transitionDelegate 設定為自身。這將允許我們出售將驅動其模態轉換的動畫師。我們還設定了 modal 的檢視框架，因此它將比全屏小。
我們現在來看看 ModalViewController：
迅速
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)
}
}
Objective-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
在這裡，我們建立了呈現的檢視控制器。另外因為 ModalViewController 是它自己的 transitioningDelegate，它還負責出售一個將管理其過渡動畫的物件。對我們來說，這意味著傳遞我們的複合 UIDynamicBehavior 子類的例項。
我們的動畫師將有兩個不同的過渡：一個用於呈現，一個用於解僱。為了呈現，呈現檢視控制器的檢視將從上方落入。而對於解僱，檢視似乎從一根繩子擺動然後輟學。因為 DropOutAnimator 符合 UIViewControllerAnimatedTransitioning 這項工作的大部分將在 func animateTransition(using transitionContext: UIViewControllerContextTransitioning) 的實施中完成。
迅速
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
}
}
}
}
Objective-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;
}
}
}
作為複合行為，DropOutAnimator 可以結合許多不同的行為來執行其呈現和消除動畫。DropOutAnimator 還演示瞭如何使用行為的 action 塊來檢查其專案的位置以及可用於移除在螢幕外移動或截斷尚未達到停滯狀態的動畫的技術所用的時間。
有關更多資訊，請參閱 2013 WWDC 會議“使用 UIKit Dynamics 的高階技術” 以及 SOLPresentingFun