复制 iOS Mail App 的 Compose Function 的风格

Question

我正在 iOS 8 上构建应用程序，并希望在创建新电子邮件/消息时复制 iOS 邮件应用程序的功能。如下图所示：compose 视图控制器呈现在收件箱视图控制器之上，但是 compose vc 并没有占据整个屏幕。有没有比修改视图控制器的框架更简单的方法呢？谢谢！

Answer 1

这个效果可以通过UIPresentationController 实现，在 iOS 8 中可用。Apple 有一个关于这个主题的 WWDC '14 视频以及在这篇文章底部找到的一些有用的示例代码（我在这里发布的原始链接不再有效）。

*该演示名为“LookInside：Presentation Controllers Adaptivity and Custom Animator Objects”。 Apple 的代码中有几个错误与过时的 API 使用相对应，可以通过将损坏的方法名称（在多个位置）更改为以下内容来解决：

initWithPresentedViewController:presentingViewController:

您可以执行以下操作来在 iOS 8 邮件应用程序上复制动画。为了达到预期的效果，下载我上面提到的项目，然后你所要做的就是改变一些事情。

首先，转到 AAPLOverlayPresentationController.m 并确保您已实现 frameOfPresentedViewInContainerView 方法。我的看起来像这样：

- (CGRect)frameOfPresentedViewInContainerView
{
    CGRect containerBounds = [[self containerView] bounds];
    CGRect presentedViewFrame = CGRectZero;
    presentedViewFrame.size = CGSizeMake(containerBounds.size.width, containerBounds.size.height-40.0f);
    presentedViewFrame.origin = CGPointMake(0.0f, 40.0f);
    return presentedViewFrame;
}

关键是您希望presentingViewController 的框架从屏幕顶部偏移，这样您就可以实现一个视图控制器与另一个重叠的外观（无需让模态完全覆盖presentingViewController）。

接下来，在AAPLOverlayTransitioner.m中找到animateTransition:方法，将代码替换为下面的代码。您可能想根据自己的代码调整一些东西，但总的来说，这似乎是解决方案：

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIView *fromView = [fromVC view];
    UIViewController *toVC   = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *toView = [toVC view];

    UIView *containerView = [transitionContext containerView];

    BOOL isPresentation = [self isPresentation];

    if(isPresentation)
    {
        [containerView addSubview:toView];
    }

    UIViewController *bottomVC = isPresentation? fromVC : toVC;
    UIView *bottomPresentingView = [bottomVC view];

    UIViewController *topVC = isPresentation? toVC : fromVC;
    UIView *topPresentedView = [topVC view];
    CGRect topPresentedFrame = [transitionContext finalFrameForViewController:topVC];
    CGRect topDismissedFrame = topPresentedFrame;
    topDismissedFrame.origin.y += topDismissedFrame.size.height;
    CGRect topInitialFrame = isPresentation ? topDismissedFrame : topPresentedFrame;
    CGRect topFinalFrame = isPresentation ? topPresentedFrame : topDismissedFrame;
    [topPresentedView setFrame:topInitialFrame];

    [UIView animateWithDuration:[self transitionDuration:transitionContext]
                          delay:0
         usingSpringWithDamping:300.0
          initialSpringVelocity:5.0
                        options:UIViewAnimationOptionAllowUserInteraction | UIViewAnimationOptionBeginFromCurrentState
                     animations:^{
                         [topPresentedView setFrame:topFinalFrame];
                         CGFloat scalingFactor = [self isPresentation] ? 0.92f : 1.0f;
                         //this is the magic right here
                         bottomPresentingView.transform = CGAffineTransformScale(CGAffineTransformIdentity, scalingFactor, scalingFactor);

                    }
                     completion:^(BOOL finished){
                         if(![self isPresentation])
                         {
                             [fromView removeFromSuperview];
                         }
                        [transitionContext completeTransition:YES];
                    }];
}

目前，我没有针对 iOS 8 之前的操作系统版本的解决方案，但如果您想出一个答案，请随时添加。谢谢。

更新（03/2016）：

上面的链接似乎不再有效。可以在此处找到相同的项目：https://developer.apple.com/library/ios/samplecode/LookInside/LookInsidePresentationControllersAdaptivityandCustomAnimatorObjects.zip

更新（12/2019）：

当在 iOS 13 上以模态方式呈现视图控制器时，这种转换样式现在似乎是默认行为。我对以前版本的操作系统不持肯定态度，但如果您想在自己的应用程序中复制此功能/转换无需编写大量代码，您既可以按原样在 iOS 13 上呈现视图控制器，也可以将该视图控制器的 modalPresentationStyle 设置为 .pageSheet，然后呈现它。

Answer 2

更新 - 2018 年 6 月：

@ChristopherSwasey 更新了 repo 以与 Swift 4 兼容。感谢 Christopher！

---

对于未来的旅行者来说，Brian 的帖子非常棒，但是我强烈建议您查看有关 UIPresentationController（有助于制作此动画）的大量重要信息。我创建了一个包含 iOS Mail 应用程序撰写动画的工作 Swift 1.2 版本的存储库。我还在自述文件中放入了大量相关资源。请在此处查看：
https://github.com/kbpontius/iOSComposeAnimation

Answer 3

我无法评论 MariSa 的回答，但我更改了他们的代码以使其真正起作用（可以进行一些清理，但它对我有用）

（斯威夫特 3）

这里又是链接：http://dativestudios.com/blog/2014/06/29/presentation-controllers/

在 CustomPresentationController.swift 中：

更新 dimmingView（使其变为黑色而不是示例中的红色）

lazy var dimmingView :UIView = {
    let view = UIView(frame: self.containerView!.bounds)
    view.backgroundColor = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.5)
    view.alpha = 0.0
    return view
}()

按照 MariSa 的指示更新 frameOfPresentedViewInContainerView：

override var frameOfPresentedViewInContainerView : CGRect {

    // We don't want the presented view to fill the whole container view, so inset it's frame
    let frame = self.containerView!.bounds;
    var presentedViewFrame = CGRect.zero
    presentedViewFrame.size = CGSize(width: frame.size.width, height: frame.size.height - 40)
    presentedViewFrame.origin = CGPoint(x: 0, y: 40)

    return presentedViewFrame
}

在 CustomPresentationAnimationController 中：

更新 animateTransition（开始/结束帧与 MariSa 的答案不同）

 func animateTransition(using transitionContext: UIViewControllerContextTransitioning)  {
    let fromVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
    let fromView = fromVC?.view
    let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
    let toView = toVC?.view

    let containerView = transitionContext.containerView

    if isPresenting {
        containerView.addSubview(toView!)
    }

    let bottomVC = isPresenting ? fromVC : toVC
    let bottomPresentingView = bottomVC?.view

    let topVC = isPresenting ? toVC : fromVC
    let topPresentedView = topVC?.view
    var topPresentedFrame = transitionContext.finalFrame(for: topVC!)
    let topDismissedFrame = topPresentedFrame
    topPresentedFrame.origin.y -= topDismissedFrame.size.height
    let topInitialFrame = topDismissedFrame
    let topFinalFrame = isPresenting ? topPresentedFrame : topDismissedFrame
    topPresentedView?.frame = topInitialFrame

    UIView.animate(withDuration: self.transitionDuration(using: transitionContext),
                               delay: 0,
                               usingSpringWithDamping: 300.0,
                               initialSpringVelocity: 5.0,
                               options: [.allowUserInteraction, .beginFromCurrentState], //[.Alert, .Badge]
        animations: {
            topPresentedView?.frame = topFinalFrame
            let scalingFactor : CGFloat = self.isPresenting ? 0.92 : 1.0
            bottomPresentingView?.transform = CGAffineTransform.identity.scaledBy(x: scalingFactor, y: scalingFactor)

    }, completion: {
        (value: Bool) in
        if !self.isPresenting {
            fromView?.removeFromSuperview()
        }
    })


    if isPresenting {
        animatePresentationWithTransitionContext(transitionContext)
    }
    else {
        animateDismissalWithTransitionContext(transitionContext)
    }
}

更新animatePresentationWithTransitionContext（再次不同的帧位置）：

func animatePresentationWithTransitionContext(_ transitionContext: UIViewControllerContextTransitioning) {

    let containerView = transitionContext.containerView
    guard
        let presentedController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to),
        let presentedControllerView = transitionContext.view(forKey: UITransitionContextViewKey.to)
    else {
        return
    }

    // Position the presented view off the top of the container view
    presentedControllerView.frame = transitionContext.finalFrame(for: presentedController)
    presentedControllerView.center.y += containerView.bounds.size.height

    containerView.addSubview(presentedControllerView)

    // Animate the presented view to it's final position
    UIView.animate(withDuration: self.duration, delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 0.0, options: .allowUserInteraction, animations: {
        presentedControllerView.center.y -= containerView.bounds.size.height
    }, completion: {(completed: Bool) -> Void in
        transitionContext.completeTransition(completed)
    })
}

Answer 4

对于 Swift 2，您可以按照本教程：http://dativestudios.com/blog/2014/06/29/presentation-controllers/ 并替换：

override func frameOfPresentedViewInContainerView() -> CGRect {

    // We don't want the presented view to fill the whole container view, so inset it's frame
    let frame = self.containerView!.bounds;
    var presentedViewFrame = CGRectZero
    presentedViewFrame.size = CGSizeMake(frame.size.width, frame.size.height - 40)
    presentedViewFrame.origin = CGPointMake(0, 40)

    return presentedViewFrame
}

和：

func animateTransition(transitionContext: UIViewControllerContextTransitioning)  {
    let fromVC = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)
    let fromView = fromVC?.view
    let toVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)
    let toView = toVC?.view

    let containerView = transitionContext.containerView()

    if isPresenting {
        containerView?.addSubview(toView!)
    }

    let bottomVC = isPresenting ? fromVC : toVC
    let bottomPresentingView = bottomVC?.view

    let topVC = isPresenting ? toVC : fromVC
    let topPresentedView = topVC?.view
    var topPresentedFrame = transitionContext.finalFrameForViewController(topVC!)
    let topDismissedFrame = topPresentedFrame
    topPresentedFrame.origin.y += topDismissedFrame.size.height
    let topInitialFrame = isPresenting ? topDismissedFrame : topPresentedFrame
    let topFinalFrame = isPresenting ? topPresentedFrame : topDismissedFrame
    topPresentedView?.frame = topInitialFrame

    UIView.animateWithDuration(self.transitionDuration(transitionContext),
        delay: 0,
        usingSpringWithDamping: 300.0,
        initialSpringVelocity: 5.0,
        options: [.AllowUserInteraction, .BeginFromCurrentState], //[.Alert, .Badge]
        animations: {
            topPresentedView?.frame = topFinalFrame
            let scalingFactor : CGFloat = self.isPresenting ? 0.92 : 1.0
            bottomPresentingView?.transform = CGAffineTransformScale(CGAffineTransformIdentity, scalingFactor, scalingFactor)

        }, completion: {
            (value: Bool) in
            if !self.isPresenting {
                fromView?.removeFromSuperview()
            }
    })


    if isPresenting {
        animatePresentationWithTransitionContext(transitionContext)
    }
    else {
        animateDismissalWithTransitionContext(transitionContext)
    }
}