Open Radar

 
Many UIs have areas that are hidden and shown as needed. Usually, one wants to move any items below a hidden item up so there's no ugly gap, or move them down when the items become visible again.

In previous Xcode versions, I've been able to implement this by adding a "top alignment constraint" in Interface Builder that aligns the hidden item's top with the top of the item above it, then changing its 'constant' to a positive value to specify that they should be next to each other, not on top of each other. Then in the code I could simply change that constraint's constant to 0 and hide the item (even with animation).

Current versions of IB no longer show an editable 'constant' for top alignment constraints. Please restore this.

For the future, it'd be great if you could provide an even nicer way to hide and show items and have whatever is above/below them move in appropriately (removing any duplicate margins that may be left over).