I use Objective C for Fashion Stash production development since eCommerce products have higher demand for stability, performance and Swift is not very mature in 2 years ago. But Apple keeps improving Swift every year and the official iOS development documentation is written in Swift now, which means Swift will be more and more stable, mature and productive in future, and a lot of companies have used Swift for their production development, there are some backend frameworks are created by Swift even.
In last weekend, I tried to write an app using Swift and Google maps API to list restaurants nearby after search, there are some ideas and thoughts about Swift development I want to share from an Objective C developer perspective.
1. Swift has more clean syntax and is more friendly to developers, Objective c is more verbose. In this case, Swift will definitely have higher efficiency in future. (like print and string
2. Some cases work in Objective C but Swift, it still takes time to be used to program in Swift even though you have years of programming experience in Objective C. (For example, you can set delegate and data source for a table view in storyboard, but have to conform to table view delegate and data source protocol explicitly in Swift)
3. A of third part libraries have Swift versions but they are not exact same with Objective C ones, therefore migration to Swift needs specific plan and sufficient time. (AFNetworking vs Alamofire)
4. Different versions of Swift have difference in details (syntax, function signatures), every update might break apps and developers should pay more attention when upgrade. (Swift 1, 2 and 3)
5. Swift becomes sexy and popular nowadays, purely code in Swift for iOS apps is the trend.
6. You can practice programming with Swift in online Swift playground/compliers.