动画自动布局与NSPopover内容同时更改 [英] Animating Auto Layout changes concurrently with NSPopover contentSize change

问题描述

我正在尝试在弹出窗口中重现iTunes 11中可导航视图的行为。我似乎找不到一种方法来使我的动画与弹出窗口的 contentSize 更改同时发生。

I'm attempting to reproduce the iTunes 11 behavior of navigable views within a popover. I can't seem to find a way to get my animation to happen at the same time as the popover's contentSize change happens, though.

我拥有的基本设置是具有两个子视图的自定义视图子类MyPopoverNavigationView：我希望弹出菜单在其间进行浏览的旧视图和新视图。弹出窗口的 contentViewController 具有MyPopoverNavigationView实例作为其视图。我这样做：

The basic setup I have is a custom view subclass MyPopoverNavigationView with two subviews: the old and new views that I want the popover to navigate between. The popover's contentViewController has a MyPopoverNavigationView instance as its view. I do this:

// Configure constraints how I want them to show the new popover view
[NSAnimationContext runAnimationGroup:^(NSAnimationContext *ctx) {
    [ctx setDuration:0.25];
    [ctx setAllowsImplicitAnimation:YES];
    [self layoutSubtreeIfNeeded];
} completionHandler:nil];

据我从《自动布局WWDC 2012》视频中得知，这是推荐的动画制作方式由于约束更改而导致视图框架的更改。它可以工作，但是动画分为两个阶段：

As far as I can tell from the Auto Layout WWDC 2012 videos, this is the recommended way to animate changes to views' frames as a result of constraint changes. It works, but the animation happens in two phases:

• 首先，弹出窗口的 contentSize 将会更改，以适应我要移至的新视图（在该视图可见之前，它们会部分遮盖现有内容）。


• 第二，

• First, the popover's contentSize will change to accommodate the new view that I'm moving to (before that view becomes visible, so it partially obscures the existing content).
• Second, the views animate as I expect, so that the constraints system I installed is satisfied.

通过设置一些断点，它看起来像 -layoutSubtreeIfNeeded 最终在弹出窗口上调用一个名为 _fromConstraintsSetWindowFrame：的私有方法，该方法在动画组之外执行弹出窗口大小的动画。我的上下文的持续时间没有得到尊重，动画直到弹出窗口的大小更改完成才发生。

From setting some breakpoints, it looks like -layoutSubtreeIfNeeded eventually calls a private method on the popover called _fromConstraintsSetWindowFrame:, which does the popover size animation outside my animation group. My context's duration isn't respected, and my animations don't happen until the popover's size change is complete.

如何获取与弹出窗口的动画一起的视图

How can I get my views to animate together with the popover's size change?

推荐答案

原来的诀窍是显式设置弹出框的 contentSize 动画和完成块的属性外部。来自示例GitHub项目的相关代码段我将其汇总起来看起来像：

Turns out the trick is to explicitly set the popover's contentSize property outside of the animation and completion blocks. The relevant snippet from the sample GitHub project I put together to figure it out looks like:

// Configure constraints for post-navigation view layout
[NSAnimationContext runAnimationGroup:^(NSAnimationContext *ctx) {
    [ctx setDuration:0.25];
    [ctx setAllowsImplicitAnimation:YES];
    [self layoutSubtreeIfNeeded];
} completionHandler:^{
    // Tear down some leftover constraints from before the transition
}];

// Explicitly set popover's contentSize so its animation happens simultaneously
containingPopover.contentSize = postTransitionView.frame.size;

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