自定义转场动画

1.设置自定义样式

    CLNewWebViewController *web = [[CLNewWebViewController alloc] init];
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:web];
    web.urlStr = model.url;
    // 自定义样式
    nav.modalPresentationStyle = UIModalPresentationCustom;
    nav.transitioningDelegate = self;
    [self presentViewController:nav animated:YES completion:nil];

2.实现UIViewControllerTransitioningDelegate代理方法。在这个方法中CoustomPresentationController是继承自UIPresentationController的自定义控制器
//这个方法是说明哪个控制器控制presentatingController、presentatedController
- (UIPresentationController *)presentationControllerForPresentedViewController:(UIViewController *)presented presentingViewController:(UIViewController *)presenting sourceViewController:(UIViewController *)source
{
    return [[CoustomPresentationController alloc] initWithPresentedViewController:presented presentingViewController:presenting];
}

 >在CoustomPresentationController实现几个方法

- (void)presentationTransitionWillBegin // 在这个方法中设置presentedView的尺寸，也就是跳转控制器的尺寸
{
    self.presentedView.frame = self.containerView.bounds;
    [self.containerView addSubview:self.presentedView];
}

- (void)presentationTransitionDidEnd:(BOOL)completed
{}
- (void)dismissalTransitionWillBegin
{}

- (void)dismissalTransitionDidEnd:(BOOL)completed
{
    [self.presentedView removeFromSuperview];
}

3.开始设置转场动画，在UIViewControllerTransitioningDelegate代理方法中实现下面2个方法

// 自定义PresentedController的动画
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{   CLAnimatedTransitioning *anim = [[CLAnimatedTransitioning alloc] init];
    anim.presented = YES;
    return anim;  // 自己遵守UIViewControllerAnimatedTransitioning协议
}

// 自定义控制器消失时的动画
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    CLAnimatedTransitioning *anim = [[CLAnimatedTransitioning alloc] init];
    anim.presented = NO;
    return anim;
}

>其中CLAnimatedTransitioning是继承自NSObject，并遵守UIViewControllerAnimatedTransitioning协议，实现协议的2个方法

#pragma mark - UIViewControllerAnimatedTransitioning
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return 1;
}

// 在这个方法中实现转场动画 ：modal和dismis都调用这个方法
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    if (self.presented) {  // 记录哪一个是即将出现的视图哪一个是即将消失的视图
        UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
        toView.mj_y = -toView.mj_height;
        [UIView animateWithDuration:1 animations:^{
            toView.mj_y = 0;
        } completion:^(BOOL finished) {
            [transitionContext completeTransition:YES];
        }];
    } else {
        UIView *fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
        fromView.mj_y = 0;
        [UIView animateWithDuration:1 animations:^{
            fromView.mj_y = -fromView.mj_height;
        } completion:^(BOOL finished) {
            [transitionContext completeTransition:YES];
        }];

    }
}