iOS8 模态视图跳转动画

     UIPresentationController是iOS8以后出来的类，可以自定义模态视图跳转动画。

      我现在Storyboard创建个视图控制器ShowInfoViewController，这就是我要跳转到的视图控制器。想要自定义跳转动画，先要设置视图控制器实例的modalPresentationStyle为UIModalPresentationCustom。然后实现设置该实例的UIViewControllerTransitioningDelegate。说到UIViewControllerTransitioningDelegate，我们需要自己实现三个类才能达成目的。

- (IBAction)doPresentShowInfoVC:(id)sender {
    
    ShowInfoViewController *showInfoVC = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"ShowInfoViewControllerSBID"];
    // 必须设置为UIModalPresentationCustom才能自定义
    showInfoVC.modalPresentationStyle = UIModalPresentationCustom;
    // 实现代理
    //ShowInfoTransitioning *showInfoTransitioning = [[ShowInfoTransitioning alloc] init];
    showInfoVC.transitioningDelegate = [ShowInfoTransitioning sharedInstance];
    
    [self presentViewController:showInfoVC animated:YES completion:nil];
    //[self performSegueWithIdentifier:@"gotoShowInfoViewController" sender:self];
}

[self performSegueWithIdentifier:@"gotoShowInfoViewController" sender:self];

是在Storyboard连线，然后实现的跳转，用此代码跳转没达到自定义动画效果，有兴趣可以试试。

最主要的就是我们自己要实现三个类了，哪三个类？

1、实现了UIViewControllerTransitioningDelegate代理的类

2、继承UIPresentationController的类

3、实现UIViewControllerAnimatedTransitioning代理的类

当然这三个类中有两个是实现协议的类，我们也可以在要跳转到下个视图控制器的VC里实现，不一定非要自己创建三个吧。

UIViewControllerTransitioningDelegate我们要实现三个代理方法

- (nullable UIPresentationController *)presentationControllerForPresentedViewController:(UIViewController *)presented presentingViewController:(nullable UIViewController *)presenting sourceViewController:(UIViewController *)source NS_AVAILABLE_IOS(8_0) {
    
    ShowInfoPresentationController *showInfoPresentationController = [[ShowInfoPresentationController alloc] initWithPresentedViewController:presented presentingViewController:presenting];
    return showInfoPresentationController;
}

设置UIPresentationController。

- (nullable id )animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source {
    
    ShowInfoAnimatedTransitioning *showInfoAnimatedTransitioning = [[ShowInfoAnimatedTransitioning alloc] init];
    // present
    showInfoAnimatedTransitioning.isPresent = YES;
    
    return showInfoAnimatedTransitioning;
}

当视图控制器present时执行动画

- (nullable id )animationControllerForDismissedController:(UIViewController *)dismissed {
    
    ShowInfoAnimatedTransitioning *showInfoAnimatedTransitioning = [[ShowInfoAnimatedTransitioning alloc] init];
    // present
    showInfoAnimatedTransitioning.isPresent = NO;
    
    return showInfoAnimatedTransitioning;
}

当视图控制器dismiss时执行动画

UIPresentationController也有它生存周期方法

// Begin
- (void)presentationTransitionWillBegin;
// 呈现
- (void)presentationTransitionDidEnd:(BOOL)completed;
// 快要销毁
- (void)dismissalTransitionWillBegin;
// 销毁
- (void)dismissalTransitionDidEnd:(BOOL)completed;

UIViewControllerAnimatedTransitioning也有两个代理方法

// 动画执行的时间
- (NSTimeInterval)transitionDuration:(nullable id )transitionContext;

// 实际的动画
- (void)animateTransition:(id )transitionContext {
    
    if (self.isPresent) {
        UIView *presentedView = [transitionContext viewForKey:UITransitionContextToViewKey];
        presentedView.frame = CGRectMake(presentedView.frame.origin.x, -(presentedView.frame.size.height), presentedView.frame.size.width, presentedView.frame.size.height);
        [UIView animateWithDuration:timeDuration animations:^{
            
            presentedView.frame = CGRectMake(presentedView.frame.origin.x, 0, presentedView.frame.size.width, presentedView.frame.size.height);
            
        } completion:^(BOOL finished) {
            
            [transitionContext completeTransition:YES];
        }];
    }
    else {
        UIView *presentedView = [transitionContext viewForKey:UITransitionContextFromViewKey];
        //NSLog(@"%@", NSStringFromCGRect(presentedView.frame));
        [UIView animateWithDuration:timeDuration animations:^{
            
            presentedView.frame = CGRectMake(presentedView.frame.origin.x, [UIScreen mainScreen].bounds.size.height, presentedView.frame.size.width, presentedView.frame.size.height);
            //NSLog(@"%@", NSStringFromCGRect(presentedView.frame));
            
        } completion:^(BOOL finished) {
            
            [transitionContext completeTransition:YES];
        }];
    }
}

github工程样例