Here is a picture of me doing it. I'm control-dragging from the constraint to the header file.
In real life I'm more likely to control-drag to the anonymous category in the implementation file, because I don't want an IBOutlet property to be public. So here's a picture of that too. Sorry, this screen shot does not show the cursor: it is at the bottom end of the stretch line.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…