在Interface Builder中添加约束时，Xcode会无限期挂起

Question

In summary, without height specified on a subview, adding constraint causes Xcode to hang.

I am using Xcode 6.3 (6D570) on Macbook Air with OSX 10.10.3, and am currently experiencing a very strange problem. I have an .xib file, which contains a view and a scroll view. Very simple, really. Here's my current setup:

Notice that the light blue/green section downwards are contained in a scroll view. In the interface builder, the bright red section does not have constraints set yet. When I try to add, for example, a vertical space constraint to the lightgray view above it, Xcode hangs.

When Xcode hangs, the Size inspector tab becomes empty and the mouse starts spinning endlessly. Here's the Size inspector screenshot when the hang happens:

After spending almost half a day, I managed to single out the problem. This problem does not happen if I add the constraints via Pin button on the bottom right corner, and specifying the height constraint of the view.

Adding constraints only work as expected if I specify / add a height constraint first. This also happens when I try to delete a constraint, for example, top space to container constraint from a label (that does not have a height constraint). I can add them just fine, but when I try to remove a constraint or delete the view, Xcode hangs.

Oh, to add more confusion: this happens frequently . As in 7 hangs out of 10.

Things I have tried:

• Remaking the view on different file
• Remaking the view on different project
• Closing all applications except Xcode, including iOS Simulator
• Restarting my computer

Things I have not tried:

• Reinstalling Xcode (or rolling back to previous version).

Should I just delete Xcode and install (download) fresh? Is this possibly a bug from the new Xcode?

Answer 1

It seems there's a bug within Xcode 6.3.0. There's an update to 6.3.1 Apr 21, 2015 that should fix this issue: