Good question — yes, there were many major changes, both technically and visually.
On the technical side, the biggest shifts were things like Objective-C → Swift, ARC, Auto Layout, size classes, Dark Mode, and more recently SwiftUI. I generally didn’t jump on everything immediately. My rule of thumb was: adopt new frameworks once they’re clearly stable and proven in real apps. Being too early often meant rewrites; being too late meant technical debt. A slightly conservative approach worked best for me.
Visually, Apple’s HIG evolved a lot: skeuomorphism → flat design → more layered, content-first UIs. I followed those changes gradually. Smaller visual updates happened continuously, but larger redesigns only when there was a real user benefit or a technical reason. Version 10 is one of those bigger moments where design and architecture changes aligned.
In hindsight, following a bit late rather than very early turned out to be the better tradeoff. Users value stability and consistency more than being on the absolute cutting edge, especially for a long-term app they rely on daily.