Setting constraints programmatically

Question

I\'m experimenting with how to use UIScrollView. After much trouble, I finally got the hang of it. But now I\'ve seem to hit another snag.

In this simple app, I have

Answer 1

It's possible to create outlets to represent layout constraints in your view controller. Just select the constraint you want in interface builder (e.g. via "select and edit" on the measurements pane of the view you are arranging). Then go to the outlets pane and drag a "New Referencing Outlet" to your code file (.h or .m). This will bind the constraint to an NSLayoutConstraint instance that you can access from your controller and adjust dynamically on the fly (generally via the constant property, which is poorly named because it's not a constant at all).

(Note that in XCode 6 you can double-click the constraint to select it for editing.)

Be careful when adjusting the layout in interface builder, however, as you may end up deleting the constraint and have to re-bind it to the outlet.