iOS gbk与utf8 互转

// gbk -> utf8- (NSString *)gbkToUtf8:(Byte *)cString{    NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);        NSData *pageData = [NSData dataWithBytes:cString length:strlen((Byte *)cString)];    NSString *string = [[NSString alloc] initWithData:pageData encoding:encoding];        return string;}// utf8 -> gbk- (NSData *)utf8ToGbk:(NSString *)string{    NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingUTF8);    return [string dataUsingEncoding:encoding];}