Learning Apple Development with C language

I have recently started learning Apple Development. But the problem is that I have never done this before. Someone suggested me to start reading this about the different things in this order:
1. Learning basic C
2. Learning basic about Objective-C
3. Learning about Xcode

Is this correct? I have also got a pdf link from Google which is a guide from Oxford University. It helps us to learn programming in C language. Is that guide best for me? I've spent too much time to learn things but they were in the wrong order. I started reading everything about Xcode and I already knew what C was.

C is one of the programming languages. Programming languages used to write instructions that the computer can perform (programs).
The reason why there are so many, because the computer basically only understand one language: machine code. However, this is not easy to write, and even harder to debug. Therefore, you have to write a program in another language, which is then translated into machine code (by a compiler). What characters in C means you have to almost read through it. It is not really complicated when one understands it, but at first it may seem rather cryptic. "{" and "}" means the start and end of a segment of code, or a list of values. All functions are recognized by having a name followed by parentheses with a list of arguments. There are also a number of other things, but it can be found in the books, pdf's or web-tutorials you find. Note that it takes a long time to learn programming. The first step is to learn the language, and this is generally the easiest. The hard part is to see how problems can be solved optimally in a specific programming language (like C) that can take far longer. But programming is not just for talking to your computer, but to tell it what to do. The computer is a calculator, neither more nor less, and that is why the language looks like mathematics.

But right now I will only be doing basically the Xcode; is it too difficult to do this? And I have also heard that C++ is best to learn about, if I want to use Xcode. BUT Xcode seems so "simple" compared to the help the programmer, if I'm not mistaken. So as you can see I really confused what should I do and what not. I don't know from where to start and where will I have to end so that I can then go for Apple Development. Please help!

Xcode is a tool for programmers. I do not work with Apple development, so I can not say anything specific about Xcode, but is not designed for Objective-C too? Learn the language you'll need, not what someone else thinks you should get used to. As a rule I recommend C, but it is not wrong to learn C++ or Objective-C. But please note that Objective-C, C++ and C are three different programming languages with different basic principles. C++ is however almost a superset of C, but Objective-C is quite another. Do not be fooled by the cosmetic similarity. What are you going to run with? As far as I know, Objective-C language will be good for developing applications on Apple's platforms, but again, I'm not really bending before the Apple development (I do mainly with C# on .NET platform). But use Xcode. Many sat with text editors and terminals for programming, but I personally see this as waste of time.