Place connections between view names to specify the way a layout flows. An empty connection (in other words, one that has been omitted) means “follow on directly.”
The first constraint you saw for Figure 5-2,
"H:[view1][view2]", uses an empty connection. There’s nothing specified between the square brackets of View 1 and the brackets of View 2. This tells the constraint to place View 2 directly to the right of View 1.
A hyphen (
-) indicates a small fixed space. The constraint
"H:[view1]-[view2]" uses a hyphen connection. This constraint leaves a standard (as defined by Apple) gap between View 1 and View 2, as shown in Figure 5-3.