iOS 自定义转场动画篇

前言: 自定义转场动画其实并不难, 关键在于能够明白思路, 也就是操作步骤. 本篇博客主要以present转场动画为例, 进行分析, 操作, 如有错误欢迎简信与我交流.

不进行修改的话, presentViewController:animated:completion:相信这个方法很多人都是用过, 称作模态推出界面, 默认都是从屏幕下方推出新的控制器.
自定义的目的就是为了修改固定的推出方式, 同时加上你想要的动画.

一个关键的概念: UIViewControllerAnimatedTransitioning控制动画的协议, 需要自己实现这个. 下面来一看看代码如何进行实现.

@interface ViewController ()<UIViewControllerTransitioningDelegate>

跳转点击方法

- (void)click:(UIButton *)sender
{
    ModelViewController *modalViewController = [ModelViewController new];
    // 指定代理
    modalViewController.transitioningDelegate = self;
    // Style = 自定义方式
    modalViewController.modalPresentationStyle = UIModalPresentationCustom;
    [self presentViewController:modalViewController
                                            animated:YES
                                          completion:NULL];
}

UIViewControllerTransitioningDelegate

// 修改动画的两个相关的协议方法, 建议仔细查看UIViewControllerTransitioningDelegate里面的注释
-(id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented
                                                                  presentingController:(UIViewController *)presenting
                                                                      sourceController:(UIViewController *)source
{
    // 推出动画 - 下面会给出代码 我参照POP动画Demo写的.
    return [PresentAnimator new];
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    // 退出 
    return [DismissAnimator new];
}
// 想要实现手势控制可在这个方法中进行修改
-(id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator {

}

关键在于动画如何实现 分别进行的实现PresentAnimator, DismissAnimator的实现.

UIViewControllerAnimatedTransitioning使用这个协议进行修改.

@interface PresentAnimator : NSObject <UIViewControllerAnimatedTransitioning>

PresentAnimator.m

// 交互所用时间
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
    return 0.5f;
}
// 具体动画方式, 上面提到的POP
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
{
    // 这里拿到即将新推出的VC的View
    UIView *toView = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
    // 这里设置退出view具体如何设置
    toView.frame = CGRectMake(0,0, SCREEN_WIDTH, SCREEN_HEIGHT);
    toView.center = CGPointMake(transitionContext.containerView.center.x, -transitionContext.containerView.center.y);
    
    [transitionContext.containerView addSubview:toView];
    // pop动画 
    POPSpringAnimation *positionAnim = [POPSpringAnimation animationWithPropertyNamed:kPOPLayerPositionY];
    positionAnim.toValue = @(transitionContext.containerView.center.y);
    positionAnim.springBounciness = 10;
    [positionAnim setCompletionBlock:^(POPAnimation *anim, BOOL finished) {
        [transitionContext completeTransition:YES];
    }];
    POPSpringAnimation *scaleAnim = [POPSpringAnimation animationWithPropertyNamed:kPOPLayerScaleXY];
    scaleAnim.springBounciness = 20;
    scaleAnim.fromValue = [NSValue valueWithCGPoint:CGPointMake(1.2, 1.4)];
    
    [toView.layer pop_addAnimation:positionAnim forKey:@"positionAnimation"];
    [toView.layer pop_addAnimation:scaleAnim forKey:@"scaleAnimation"];
}

DismissAnimator.m

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
    return 0.5f;
}

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
{
    // fromVC 很好理解吧?? 就是从哪个控制器推过来回到哪里去.
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    POPBasicAnimation *offscreenAnimation = [POPBasicAnimation animationWithPropertyNamed:kPOPLayerPositionY];
    offscreenAnimation.toValue = @(-fromVC.view.layer.position.y);
    [offscreenAnimation setCompletionBlock:^(POPAnimation *anim, BOOL finished) {
        [transitionContext completeTransition:YES];
    }];
    [fromVC.view.layer pop_addAnimation:offscreenAnimation forKey:@"offscreenAnimation"];
}

顺便值得一提的是UINavigationController转场的动画也是可以自定义的. 通过这个
UINavigationControllerDelegate来完成

    // 签订这个协议
    self.navigationController.delegate = self;

- (id<UIViewControllerAnimatedTransitioning>) navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC
{
    
    if (operation == UINavigationControllerOperationPush) {
        // 动画的方式不变
        return [PresentAnimator new];
    }else{
        return nil;
    }
}