UIView `readableContentGuide` in Interface Builder?

问题

The iOS 9 readableContentGuide is a UILayoutGuide (essentially, a thing you can pin constraints to) that all UIViews have. The idea is to keep subviews with text from being too wide on iPad in landscape.

It's easy to configure this in code (v1 is the subview, v is its superview):

NSLayoutConstraint.activateConstraints([
    v1.topAnchor.constraintEqualToAnchor(v.readableContentGuide.topAnchor),
    v1.bottomAnchor.constraintEqualToAnchor(v.readableContentGuide.bottomAnchor),
    v1.rightAnchor.constraintEqualToAnchor(v.readableContentGuide.rightAnchor),
    v1.leftAnchor.constraintEqualToAnchor(v.readableContentGuide.leftAnchor)
])

Now then. So far so good. However... In two different WWDC videos, it is claimed quite explicitly that you can configure pinning a subview to its superview's readableContentGuide in Interface Builder.

But they don't explain how you do that.

So my question is: How do you do it?

回答1:

Pin the subview's edges to the superview's margins as usual.

Now, in the superview's Size inspector, check the Follow Readable Width checkbox:

来源：https://stackoverflow.com/questions/31569597/uiview-readablecontentguide-in-interface-builder