Create a new Objective-C project : Example.xcodeproj

From this project, Learn and study how to do programming with Objective-C language in the Xcode development environment of Apple Mac OS X.
1. Modify the new .gitignore file.

2. Ignore the tracking for .xcuserstate type of files.
添加一個README文件。

去掉對*.xcuserstate類型的git tracking.
Remove the tracking for .xcuserstate type of files.
對比研究變量的內存分配 ： 棧上分配 和 堆上分配。

變量的作用域
Merge branch 'develop' into Studying_Objective_C_Programming

Conflicts:
	.gitignore  ===> Solved, and uniform it in all branches.
Merge branch 'Studying_Objective_C_Programming' into develop
Merge pull request #2 from xu-zan/Studying_Objective_C_Programming

同意Studying_Objective_C_Programming branch合併到develop分支中去。