实现了在cocoa中的shell运行。示例中使用的就是shell命令中的ping指令，最终将其显示在textView中-Achieved in the cocoa in the shell to run. Sample is used in shell command ping and eventually be displayed in the textView

实现对文本框的一些丰富的操作，代码带有注解，方便读写-Achieve some rich text box operation code annotated, easy to read and write