Swift library for converting GK4-coordinates into WGS84 latitude and longitude, and vice versa.
import GaussKrueger
let coord = WGSCoordinate(latitude: 52.502133988116455, longitude: 13.342517405215336)
let gk = coord.asGK
// ---
let gk = GKCoordinate(x: 4591270, y: 5819620)
let wgs = gk.asWGSgausskrueger is available through Cocoapods, Carthage/Punic and Swift Package Manager, take your pick.
// Cocoapods
pod 'gausskrueger'
// Carthage
github "kiliankoe/gausskrueger"
// Swift Package Manager
.Package(url: "https://github.com/kiliankoe/gausskrueger", majorVersion: 0)This is basically a clone of juliuste/gauss-krueger (which in turn seems to be from here) with a few modifications to make it valid Swift.