Convert Your Mobile app from objective C to Swift. Swift and Object-C are the two most popular programming languages that are used for iOS app development. However, in the past few years, application developers are switching to Swift programming language over the object-c language. Because of this, the migration process has also been increased for converting an objective-C app into a swift application. Today many iPhone app development agency are opting for this process as well. Let’s dive into the process of converting your mobile app from objective-c to Swift: Converting one Class at a Time: Instead of converting all the class at once, it’s better to convert one class at a time. As Swift cannot have subclasses, you can use two files that contain an interface section in the header file & implementation section in another.