Hello do i need to know Object c language or Swift is enough ? is Swift Does the same things ?

Objective-C and Swift are different, but if you know Swift already, good. If you don't know Objective-C or Swift, I'd start out by learning Objective-C. Swift is a fairly new language and if you were looking for a job, you're more than likely to find an employer who is looking for an Objective-C developer than Swift.

ok thank you

You will still need to know objective-C for the next few years.

http://www.bignerdranch.com/blog/ios-developers-need-to-know-objective-c/

You can’t do everything in Swift. For example, if you want to use a library of C++ code in your application, you will need to talk to the C++ objects from Objective-C. Swift can call C functions, but I believe that if you are working with a lot of C functions and types, you will want to code in Objective-C.

The community talks in Objective-C. There are thousands of useful Objective-C snippets on StackOverflow and iOS dev blogs everywhere. Objective-C is the language we have used for the last six years to describe to each other how the Cocoa Touch libraries work. If you can’t read Objective-C, you won’t be able to understand this trove of knowledge.

The frameworks are written Objective-C. When you have a bug, it often doesn’t rear its ugly head until execution is deep in Apple’s code. If you want to understand what the debugger is telling you, you will need to understand Objective-C. Objective-C is stable and well-tested. Swift looks great, but the language is evolving and the compiler is immature. If I were making a significant bet on developing an app this year, I would still use Objective-C.