This article gathers together 25 tips and tricks that you can use to improve the performance of your apps, in the form of a handy checklist.
So keep reading to give your future apps a nice boost!
They cover basics (reuseIdentifiers; Fat XIBs; Don't block the main thread), intermediate (lazy views; caching; shadow path) as well as advanced (avoid date formatters - which I need to do on Trip Wallet)
There are lots of other good tutorials and tips on that site, it's well worth looking around.
[^1] I'm not sure if it's "Ray Wenderlich's site" or just "Ray Wenderlich" - there are lots of people writing on there, so it's not just one person.