NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding (kCFStringEncodingGB_18030_2000);//GB2312,GBK NSISOLatin1StringEncoding NSUTF8StringEncoding等 2.截取字符串
substringWithRange substringToIndex:<#(NSUInteger)#> substringFromIndex:<#(NSUInteger)#>3.分割字符为NSArray数组
componentsSeparatedByString:<#(NSString *)#>4.替换字符
stringByReplacingOccurrencesOfString