iphone 编码的转码

NSURL *url = [NSURL URLWithString:urlStr];NSData *data = [NSData dataWithContentsOfURL:url];NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);NSString *retStr = [[NSString alloc] initWithData:data encoding:enc];