I have tried iSwift and it is not very good and it is not its fault. Swift introduced generics, powerful enums, high-order functions such as map, filter and so on.
It is purely impossible to convert Objective-C code to idiomatic Swift code. Even if it works, you will end up with Swift code that is just horrible.
It is purely impossible to convert Objective-C code to idiomatic Swift code. Even if it works, you will end up with Swift code that is just horrible.