objective-c的utf8转gbk（转载）

objective-c的utf8转gbk：

- (NSString *) utf2gbk:(NSString *)string

{
    NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
    NSString *retStr = [[[NSString alloc] initWithData:data encoding:enc] autorelease];
    return  retStr;   
}