中文转UTF

 1， 

  NSString *strtitle=@"哈利波特";

    strtitle=[strtitleurlEncodeString];

2，

    NSString *strsearch=searchBar.text;

    NSStringEncoding chineseEncoding=CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);

    strsearch=[strsearchstringByAddingPercentEscapesUsingEncoding:chineseEncoding];

    NSURL *url=[NSURLURLWithString:[NSStringstringWithFormat:@"http://php.weather.sina.com.cn/xml.php?city=%@&password=DJOYnieT8234jlsK&day=0",strsearch]];

    NSString *str=[NSStringstringWithContentsOfURL:urlencoding:NSUTF8StringEncodingerror:nil];

GBK转ＵＴＦ８

NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    NSString *string = [[NSString alloc] initWithData:data encoding:enc];
    NSData *datame = [string dataUsingEncoding:NSUTF8StringEncoding];