I think you do have to learn a bit of the basics of Objective-C. The sole reason being that most of Apple's frameworks are currently written in Objective-C, as

I think you do have to learn a bit of the basics of Objective-C. The sole reason being that most of Apple's frameworks are currently written in Objective-C, as well as most tutorials and example material. You'd have an easier time converting Objective-C code to Swift code if you understand the basics of Objective-C. You'd also have an easier time finding solutions to problems on sites like StackOverflow, which already has a wealth of Obj-C questions and answers. But in the end you don't have to become an Objective-C pro. Once you feel comfortable using the language, you could start focusing on Swift.