Porting an iOS app to macOS

About six weeks ago (2 weeks or so before WWDC), my client asked me to port an enterprise app I wrote for iOS to macOS. I haven’t done macOS work for a long time, but how hard could it be? In the last few years, a number of iOS-like technologies have come to macOS; while they aren’t named the same, many things function similarly like NSViewController (UIViewController), NSTableView (UITableView), NSTableCellView (UITableViewCell), etc. All of my iOS apps for this client are written in Swift, so it made a lot of sense to use Swift for this macOS app.

Getting started with the project took about a week to get familiar with macOS again, but then things started moving. The first thing I did after the app ran was to make a version of my framework that I use across 5 iOS apps (models, networking, methods, etc.) over to the Mac which wasn’t difficult; I only had to do a few platform specific defines for the files I moved over (I didn’t move the UI pieces over). Once the basic app was running, I started the UI and had real data showing up within a few weeks from start. I took a number of pieces of the iOS app, copied the code and pasted it into the Mac app. The number of changes for these pieces were minimal (.stringValue instead of .text on the NSTextField vs UILabel), but I was quite pleased how I was able to reuse the code.

From start to basically feature parity with iOS took about 5 weeks. I’m sure that there are things that I’d change such as doing extensions on classes instead of copying/pasting code as I’ll have to maintain both apps going forward, but that could obscure how things work. I am extremely pleased with how well this project is going (it hasn’t been deployed, yet).

At WWDC Marzipan was revealed and it looks like it will allow many iOS apps to run on macOS. This, of course, would have helped me get my app up and running, but would it feel like a Mac app? While not every app is as straight forward as the one I ported, developers that want to move their apps to macOS today have nothing stopping them.

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