启动屏幕XIB:缺少宽度/高度限制(Xcode 6) [英] Launch Screen XIB: Missing Width / Height Constraints (Xcode 6)

问题描述

使用 Xcode 6 ，我正在构建针对 iOS8 的iOS应用.

Using Xcode 6, I am building an iOS app that targets iOS8.

我正在处理LaunchScreen.xib文件，该文件是通过菜单File > New > File > iOS - User Interface - Launch Screen创建的.启用使用自动布局".

I'm working on a LaunchScreen.xib file, created from the menu: File > New > File > iOS - User Interface - Launch Screen. "Use Auto Layout" is enabled.

在XIB的主UIView内，我放置了UIImageView.我想添加宽度和高度约束，以使UIImageView与容器具有相同的大小.但是，Xcode不允许我这样做:我只能使用间距和对齐方式.

Inside the XIB's main UIView, I've placed a UIImageView. I would like to add width and height constraints, so that the UIImageView has the same size as the container. However, Xcode doesn't let me do that: I can only work with spacing and alignment.

这是我看到的:

我做错了什么?为什么看不到以下菜单?

What am I doing wrong? Why can't I see a menu like the following?

我知道可以通过将容器的前导空间，尾随空间，顶部空间和底部空间设置为0来达到相同的结果，但是我也想了解这里发生的事情.

I know I could reach the same result by setting leading space, trailing space, top space, and bottom space to container to 0, but I would also like to understand what's happening here.

推荐答案

Xcode 7 + 默认为启动屏幕的情节提要文件.
如下所述，与XIB不同，情节提要文件允许您将宽度和高度约束设置为根UIView.

Xcode 7+ defaults to a Storyboard file for the Launch Screen.
As explained below, unlike XIBs, Storyboard files allow you to set width and height constraints to the root UIView.

对于XIB为何如此表现，我还没有找到官方的解释，当根上有UIView时.
在我看来，很奇怪的是，我们提供的默认设置(LaunchScreen.xib)的行为与我们习惯的情节提要完全不同.

I haven't been able to find an official explanation as to why XIBs behave like that, when they have a UIView at the root.
What looks weird to me is that what we are provided with as a default (LaunchScreen.xib) isn't set up to behave exactly like the Storyboards we've got used to.

我选择的第一个解决方案是使用情节提要板而不是XIB绘制启动屏幕:

The first solution I opted for was using a Storyboard to draw the Launch Screen, instead of a XIB:

• 删除LaunchScreen.xib
• 创建LaunchScreen.storyboard(菜单:File > New > File > iOS - User Interface - Storyboard)
• 转到项目属性，选择导航至目标的常规属性，然后在启动屏幕文件"组合框中选择LaunchScreen.storyboard
• 打开LaunchScreen.storyboard，添加一个View Controller，然后确保以勾选是初始View Controller框"
• 您现在可以在视图控制器"的视图"上作为启动屏幕"使用，并且会得到我最初正在寻找的宽度和高度约束

• Delete LaunchScreen.xib
• Create a LaunchScreen.storyboard (Menu: File > New > File > iOS - User Interface - Storyboard)
• Go to your project properties, select navigate to your target's general properties and select LaunchScreen.storyboard in the "Launch Screen File" combo box
• Open LaunchScreen.storyboard, add a View Controller, and make sure to tick the "Is Initial View Controller Box"
• You can now work on the View Controller's View as your Launch Screen, and you'll get the width and height constraints I was initially looking for

另一种解决方案是删除LaunchScreen.xib中的默认UIView，然后将其替换为View Controller.
与前面的情况一样，如果这样做，则可以在View Controller的View上进行操作，然后将获得通常的约束菜单.

An alternative solution is removing the default UIView in LaunchScreen.xib and replacing it with a View Controller.
Just like in the previous case, if you do so, you can work on the View Controller's View, and you'll get the usual constraint menu.

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