复制iOS邮件应用程序的撰写功能的风格 [英] Replicating the style of the iOS Mail App's Compose Function

问题描述

我正在iOS 8上构建一个应用程序，并且正在寻找在创建新的电子邮件/消息时复制iOS邮件应用程序的功能。如下所示：组合视图控制器显示在收件箱视图控制器的顶部，但组合vc不占用整个屏幕。有没有更简单的方法来做这个，而不是用视图控制器的框架进行黑客攻击？谢谢！

I'm building an app on iOS 8 and am looking to replicate the functionality of iOS's mail application when creating a new email / message. It's shown below: the compose view controller is presented on top of the inbox view controller, but the compose vc doesn't take up the whole screen. Is there any easier way to do this than hacking around with the frames of the view controllers? Thanks!

推荐答案

这个效果可以通过在iOS 8中提供的 UIPresentationController 来实现。有一个关于这个主题的WWDC '14视频以及这个帖子底部找到的一些有用的示例代码（我在此发布的原始链接不再有效）。

This effect can be achieved with UIPresentationController, made available in iOS 8. Apple has a WWDC '14 video on this topic as well as some useful sample code found at the bottom of this post (original link I had posted here no longer works).

*演示称为LookInside：演示控制器适应性和自定义动画对象。苹果代码中有一些错误对应于过时的API使用，可以通过将破坏的方法名称（在多个位置）更改为以下内容来解决：

*The demo is called "LookInside: Presentation Controllers Adaptivity and Custom Animator Objects." There are a couple bugs in Apple's code that correspond to outdated API usage, which can be solved by changing the broken method name (in multiple places) to the following:

initWithPresentedViewController：presentsViewController：

您可以在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。

Here's what you can do to replicate the animation on the iOS 8 mail app. To achieve the desired effect, download the project I mentioned above, and then all you have to do is change a couple things.

首先，转到AAPLOverlayPresentationController.m，并确保您已经实现了 frameOfPresentedViewInContainerView 方法。我看起来像这样：

First, go to AAPLOverlayPresentationController.m and make sure you've implemented the frameOfPresentedViewInContainerView method. Mine looks something like this:

- (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presentationViewController的框架与屏幕顶部，所以您可以实现一个视图控制器重叠的外观（没有模态完全覆盖presentationViewController）。

The key is that you want the frame of the presentedViewController to be offset from the top of the screen so you can achieve the look of one view controller overlapping the other (without having the modal fully cover the presentingViewController).

接下来，在AAPLOverlayTransitioner.m中找到 animateTransition：方法，并将代码替换为以下代码。您可能希望根据自己的代码调整一些内容，但总体而言，这似乎是解决方案：

Next, find the animateTransition: method in AAPLOverlayTransitioner.m and replace the code with the code below. You may want to tweak a few things based on your own code, but overall, this appears to be the solution:

- (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];
                    }];
}

我现在没有一个操作系统版本的解决方案到iOS 8，但如果想出一个，请随时添加一个答案。谢谢。

I don't, at this time, have a solution for OS versions prior to iOS 8, but please feel free to add an answer if you come up with one. Thanks.

更新：

看起来好像上面的链接不再作品。可以在这里找到同一个项目： https://developer.apple.com/library/ios/ samplecode / LookInside / LookInsidePresentationControllersAdaptivityandCustomAnimatorObjects.zip

It appears as though the link above no longer works. The same project can be found here: https://developer.apple.com/library/ios/samplecode/LookInside/LookInsidePresentationControllersAdaptivityandCustomAnimatorObjects.zip

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