"Add New Constraints" checkboxes and fields are disabled

Question

I have a project I am upgrading from Xcode 4.6.3 to Xcode 6.1.1. I opened it in Xcode 6.1.1, and opened each .xib. The format of each .xib changed as expected. I want to attempt to use auto layout. Use Auto Layout is checked and so is Use Size Classes. I changed every appropriate object from Alignment Frame to be Alignment Rectangle.

For a while I couldn’t add any constraints. Then after some trying I could add a few. See the screenshot.
For the selected View, I cannot add a constraint. The Add New Constraints checkboxes and fields are disabled. Only Update Frames is available to be changed. I can’t add an alignment constraint either. Ctrl-drag a line off the view does not add a constraint either. Notice the View height of 411. If I select another object, then select the View again the height will change to be the height of the parent tab bar less. If I keep doing that the height gets smaller and smaller, then Xcode crashes. How can I add a constraint to this view?

The Tab Bar X, Y, Width, and Height are disabled. When I change the Height of the Assigned View Controller View, the Tab Bar Y changes to that value minus the Tab Bar Height of 49. When I select the View, again it’s Height is now 49 less. Select the Tab Bar, it’s Y is now 49 less. And so on. How do I set the dimensions of the Assigned View Controller View that will stick when I cannot add contraints?

Answer 1

I had the same issue. In my case, the view layout setting was set to Translate Mask Into Constraint. I resolved it by changing it to Automatic in Size Inspector.

Answer 2

Xcode 12, Xcode 13

For UI elements where adding constraints are disabled, check Layout in the Size Inspector:

If Layout is set to Autoresizing Mask change to Inferred.

or

Inferred(Constraints) - The UI element already has one or more constraints. Inferred(Autoresizing Mask) - The UI element currently has no constraints.