Both. Swift should be your focus, but you need to know enough Obj-C to translate doc (hopefully a short-term problem) and you need to interop with Obj-C. Swif

Both. Swift should be your focus, but you need to know enough Obj-C to translate doc (hopefully a short-term problem) and you need to interop with Obj-C. Swift will be the more productive language, but will have a bigger learning curve (it is a bigger language, more concepts). Obj-C is not that hard to learn these days, a lot of the annoyances are taken care of for you (ARC, synthesize, etc.) Good luck and have fun!