The Per Rewrite Diaries: Day 21

This post is part of a series about rewriting my iOS app, Per. Per is a price per unit comparison app with a bunch of neat convenience figures, but it hasn’t been updated in years, so I’m rewriting it from scratch to eliminate a bunch of technical debt. Just because it’s not an open-source app doesn’t mean I can’t share what I learn as I go!

See the rest of the series here.

Refactoring layout code

I’m a little short on time today, so I’ll grab some low-hanging fruit for a quick win. Yesterday, I wrote that “the ProductDetailContentViewController is kinda sloppy — some of its UI is from an embedded custom view, and some of it is created in viewDidLoad(), which should at least be refactored out into separate setupView() and setupConstraints() methods.”

That’s easy enough. I’m marking those setup functions as private, and taking advantage of NSLayoutConstraint.activate() for setting up and activating constraints. I don’t think it’s necessarily less readable than chaining .isActive = true to the end of each constraint call, but as an array I can fold the code in the editor so it takes up less space, which I something I take advantage of.

So that’s one papercut fixed! Just over a week to go before the end of the month; let’s see how close I can get to the current shipping features! Tomorrow I’ll tackle one of the FIXME issues — specifically, making ProductList.add() throw on trying to add a mismatched-unit ProductItem.