Swiftify

It is recommended to use Swiftify in any situation that requires iOS development because even if you develop just in Swift or just in Objective-C, it could be helpful for researching and investigating purposes.Additionally, if you need to convert big quantities of code from Objective-C to Swift, this tool will optimise that work. It will not translate a whole class of 2000 lines perfectly, but after converting it you can review the code and modify the lines that have not been properly converted, making you save more than the 50% of the time in that case.I've not been able to test it properly as I only used the trial version and it is really limited.

Swiftify is good converter, there's a room for imrovement, but it helps a lot.