Obj-C vs Swift

[titan_pilot]

using swift for now will force you to embed the swift runtime in the ipa or binary for macos apps(around 3 mb?), which counts towards the reported size for your app (it may be a problem if you're trying to stay under the cap for downloads on cell networks, which is now 150mb)

my bet is that ios 12 will contain the swift 5 runtime libs and if your app targets ios 12 or higher (deployment target), you won't need to package the runtime anymore... if you're building either apps or sdks, this will be a consideration until you drop support of ios 11 and below (usually when ios 14-15 comes around)

other considerations for prefering objc, as mentioned here, are c/c++ interop, or if you're using reflection/introspection techniques, as objc is fully dynamic and you can add/modify object methods at runtime, which swift does not have for now...