when using constraints in ios autolayout, are there benefits to shorter constraint chains?

Question

For example, when I want to make the leading value of 10 different UI elements match, should I be constraining 9 of them to the first item's leading value, or should I create a chain 1 -> 2 -> 3 -> 4 -> 5 -> 6 ...etc.

I was wondering about the performance differences and whether I should prefer one for maintenance reasons.

Answer 1

It's very difficult to answer an abstract question.

If you want the leading of 10 UI elements to match...

First, you're almost certainly better off putting them in a UIStackView... you constrain the stack view's leading and you're done.

Second, if there is a reason you don't want to (or can't) use a stack view, then the answer depends on what else you might be doing.

Suppose you want element 3 "indented" 40-pts?

• If they're all aligned to element 1, you only change the constant of element 3.
• If they're "chained" you have to change the constants of elements 3 and 4.

Suppose you want elements 5 through 10 "indented" 40-pts?

• If they're all aligned to element 1, you have to change the constants of elements 5, 6, 7, 8, 9 and 10.
• If they're "chained" you only change the constant of element 5.

Suppose you want to "insert" an element between 3 and 4? Or remove element 6?

Suppose any of the above - or any number of other possibilities - are "conditional" and factor into the alignment?

As you can see, the preference of one over the other will depend on many things.