App Store Connect requires four different screen resolutions for preview videos -- full screen iPhone, home button iPhone, iPad and Mac. Will the app store display the video for a different device than the device the app store is viewed on? For example, if I create only an iPad video, will it display to users browsing on an iPhone? Or do I really need to record and edit four separate versions of each video for all users to see it?

I've been publishing iOS apps since 2009, a couple of which have grown quite large in that time (over 200 classes in the largest), all in the original Objective-C language. I've kept an eye on Swift and started some new projects in Swift, but the task of rewriting my existing apps has been too big to make a priority. Then this year, the economic slowdown from COVID has given me more time, and I've decided to tackle it this fall. At the same time, I've been noticing a stronger bias toward Swift in Apple's documentation and code samples. For example, new framework documentation only includes Swift code samples, while older documentation includes both. This confirms that the time is right to make this investment. I've found some good tips for managing the migration, including this article: https://developer.apple.com/documentation/swift/migrating_your_objective-c_code_to_swift My question is more general: if you migrated a large project, I'd be curious to hear something about your overall experience. What made you decide to go for it, was it easier or harder than you expected, are you happy with the results? BTW, I ported some of my apps to Android back in 2013, so I have some sense of the scale of the project. I'm expecting this to be easier than that since most of the classes and frameworks are the same, but with slightly different names and a very different syntax. Simply retyping thousands of lines of code with a new syntax can be exhausting, though.