README.md in objcthin-0.2.0 vs README.md in objcthin-0.3.0

@@ -4,10 +4,14 @@
 
 这个脚本可以自动的帮你找出当前项目中不在使用的selector和class，支持debug版本的APP包和LinkMap文件。
 
 ## Installation
 
+this script use ruby 2.4.* above, please check you ruby version:
+
+    $ ruby -v
+
 Add this line to your application's Gemfile:
 
 ```ruby
 gem 'objcthin'
 ```
@@ -24,12 +28,18 @@
 
 find unused selector:
     
     $ objcthin findsel apppath(the execuse app path)
     
+    # add the special prefix
+    $ objcthin findsel apppath(the execuse app path) --prefix='UI'
+    
 find unused class:
       
-    $ objcthin findclass apppath(the execuse app path)  
+    $ objcthin findclass apppath(the execuse app path) 
+     
+    # add the special prefix
+    $ objcthin findclass apppath(the execuse app path) --prefix='UI'
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.