I found these tutorials to create our own cocoapod:
but for me none of them helps, as they create fresh xcode project using pod lib create. I have my own xcode project and I need to setup in that rather than create a fresh one.
1.Delete following files/folder that pod created. 
2.Make sure your Podfile available.
3.Use this command:
pod install Updated
If you didn't have installed pod in your project. Do like following:
1.Use pod setup in your project root folder.
2.Edit Podfile
3.Use this command:
pod install 
Try to do like this:
1.Run the command on Terminal:- sudo gem install cocoapods
After successfully install CocoaPods
2.Go to that folder where your existing project is saved in your System.
3.After that Run the command for creating Pod file:- Touch podfile
4.After Creating Pod file run the next command:- Open podfile
It will open pod file and here Put the below line and save that file using command+S
source 'https://github.com/CocoaPods/Specs.git'
platform :ios, ‘8.0’
use_frameworks!
pod 'Alamofire', '~> 2.0.2’
5.After that run the final command in your Terminal:- pod install
It will take some time to install that file after that once install the all file close the xcode project and again open that project, click on the .xcworkspace extension file.
