The only thing that doesn't work in iOS7 (except for the new iOS8 APIs obviously) is frameworks. This can cause an issue on larger projects because the Swift co

The only thing that doesn't work in iOS7 (except for the new iOS8 APIs obviously) is frameworks. This can cause an issue on larger projects because the Swift compile can take some time but there are workarounds for during development. Supporting iOS7 and iPhone 4S's is no real problem in Swift. This frameworks issue is not Swift specific though, it also applies to Objective-C although that has support for incremental builds so it isn't such an issue.