自定义转场动画（二）

之前介绍一篇文章 自定义转场动画（一），主要介绍了Present的转场动画。今天介绍一下有关Push的转场动画。

准备：首先要两个UIViewController和一个继承与UIPercentDrivenInteractiveTransition的类。

ViewController1ViewController2PushTransitionAnimator

PushTransitionAnimator
.h

@interface PushTransitionAnimator : UIPercentDrivenInteractiveTransition<UIViewControllerAnimatedTransitioning,UIViewControllerTransitioningDelegate,UIGestureRecognizerDelegate>@property (nonatomic, assign) BOOL isPop;//是push还是pop

.m
完成UIViewControllerAnimatedTransitioning协议

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext{    return self.transitionDuration;}//这里实现从下往上的Push- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext{    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];    UIViewController *toViewController   = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];    self.targetViewController = toViewController;    [self creatDragGesture];    UIView *containerView = [transitionContext containerView];    if (!self.isPop) {        CGRect startRect;        [containerView addSubview:toViewController.view];        toViewController.view.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;        startRect = CGRectMake(0, CGRectGetHeight(containerView.bounds), CGRectGetWidth(containerView.bounds), CGRectGetHeight(containerView.bounds));        toViewController.view.frame = startRect;        [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{            fromViewController.view.alpha = self.behindViewAlpha;            toViewController.view.frame = CGRectMake( 0, 0,                                                     CGRectGetWidth(toViewController.view.frame),                                                     CGRectGetHeight(toViewController.view.frame) );        } completion:^(BOOL finished) {            [fromViewController endAppearanceTransition];            [transitionContext completeTransition:![transitionContext transitionWasCancelled]];        }];    }else{        [containerView addSubview:toViewController.view];        toViewController.view.alpha = self.behindViewAlpha;        CGRect endRect;        endRect = CGRectMake(0, CGRectGetHeight(fromViewController.view.frame), CGRectGetWidth(fromViewController.view.frame), CGRectGetHeight(fromViewController.view.frame));        [toViewController beginAppearanceTransition:YES animated:YES];        [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{            toViewController.view.alpha = 1.0f;            fromViewController.view.frame = endRect;        } completion:^(BOOL finished) {            [toViewController endAppearanceTransition];            [transitionContext completeTransition:![transitionContext transitionWasCancelled]];        }];    }}

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如何使用

Push与Present最直观的区别就是有导航的参与。所以我们要在ViewController1中准守 UINavigationControllerDelegate 协议。

初始化 设置导航代理

- (void)viewDidLoad {    [super viewDidLoad];        _animator                    = [[PXPushTransitionAnimation alloc] initWithModalViewController:self];    _animator.dragable           = YES;    _animator.bounces            = YES;    _animator.behindViewAlpha    = 0.3;    _animator.transitionDuration = 0.35f;    _animator.behindViewScale    = 1.0f;    ....}- (void)viewDidAppear:(BOOL)animated{    [super viewWillAppear:animated];    self.navigationController.delegate        = self;}

实现代理方法

#pragma mark - **************** Navgation delegate- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController                                  animationControllerForOperation:(UINavigationControllerOperation)operation                                               fromViewController:(UIViewController *)fromVC                                                 toViewController:(UIViewController *)toVC{    if (operation == UINavigationControllerOperationPush) {        self.animator.isPop = NO;//push    }else if (operation == UINavigationControllerOperationPop){        self.animator.isPop = YES;//pop    }    return self.animator;}

有关手势的返回交互可以参考present，原理相同。