Even though Apple has been heavily advertising Swift, it seems like the company is still not ready to implement this programming language into its own iOS apps.
According to a software engineer Ryan Olson, who recently published a blog post regarding this issue, the Calculator app is the only part of iOS 9.2 that includes any Swift code. This application is almost “pure Swift” with only 2 out of 22 classes written in Objective-C, which was Apple’s previous programming language of choice.
Most of other Apple’s optional apps are generally written in Objective-C, such as the official WWDC app. Even though the company said that WWDC was re-done in the new programming language, out of 281 classes, only 6 are actually written in Swift. It is the similar situation with the Apple Store app, which is the final app where this new programming language can be found.
This problem might have several causes, such as the Swift Application Binary Interface not being still finished. However, this should be resolved by the third major version. In addition, there is also no 32-bit Swift runtime for OS X.
According to the blog post, we should see this situation changed in the next major version of iOS. Since most of iOS is being showed to the public once a year, we have to wait until this year’s WWDC in June.