Constraint/Autolayout bar hidden, Xcode 6

Make sure auto layout is enabled if you want to use the auto layout controls.

Autolayout Enabled:

Autolayout Disabled: Note the controls are missing.

If you're looking to use auto layout with UIScrollView it should probably be asked in another question. But very briefly, when using auto layout, the place most people trip up is that UIScrollView determines its content size based on your constraints within the scrollview. If those are set right, you should be good to go.

Good luck.

Quiting Xcode and reopening worked for me.