How to use NSString and NSMutableString

NSString-----------------------------------------------------------------------------------------------------------------------

基本操作：

>> -(int) length

>> -(const char*) cString

>> -(const char*) UTF8String 以UTF-8形式返回字符串，Mac OS X所有的底层系统都能处理以UTF-8编码的char *

>> -(NSString *) stringByAppendingString:(NSString *) aString

构建并调试（Build and debug） #-Y

处理字符串的字串

-(NSRange) rangeOfString:(NSString *) aString

-(NSString *) substringFromIndex: (unsigned) index

-(NSString *) substringToIndex: (unsigned) index

-(NSString *) substringWithRange:(NSRange) range

操作文件

-(NSString *) lastPathComponent

-(NSString *) pathExtension

-(NSString *) stringByStandardizingPath

-(NSString *) stringWithContentsOfFile:(NSString *) path

-(BOO) writeToFile:(NSString *) path atomically:(BOOL) flag

NSMutableString--------------------------------------------------------------------------------------------------------------

-(void) appendString:(NSString *) aString

-(void) deleteCharactersInRange:(NSRange) range

-(void) insertString:(NSString *) aString atIndex:(unsigned) index