サーバーからのデータをjsonで解析してiPhoneアプリで使用し、検索テキストフィールドを取得してサーバーに投稿し、テキストと一致して以下のデータを返すのは私のiPhoneコードです
    NSString*searchText=searchTextField.text;
NSString *post =[[NSString alloc] initWithFormat:@"searchCode=%@",searchText];
NSURL *url=[NSURL URLWithString:@"http://www.celeritas-solutions.com/pah_brd_v1/productivo/searchCatalog.php?"];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init] ;
[request setURL:url];
[request setHTTPMethod:@"POST"];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[request setHTTPBody:postData];
    NSError *error;
    NSURLResponse *response;
    NSData *urlData=[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
    NSString *data=[[NSString alloc]initWithData:urlData encoding:NSUTF8StringEncoding];
    NSData* myData=[data dataUsingEncoding:NSUTF8StringEncoding];
    NSString *json_string = [[NSString alloc] initWithData:myData encoding:NSUTF8StringEncoding];
    NSArray *dataArr=[json_string JSONValue];
    for (int i=0; i<[dataArr count]; i++) {
        if (!dataArr || !dataArr.count){
            if(resultArray!=nil){
                resultArray=nil;
                resultArray=[[NSMutableArray alloc]init];
            }
        }
        NSDictionary *dict=[dataArr objectAtIndex:i];
        ObjectData *theObject =[[ObjectData alloc] init];
        [theObject setCategory:[dict objectForKey:@"category"]];
        [theObject setSub_Category:[dict objectForKey:@"sub_Category"]];    
        [theObject setContent_Type:[dict objectForKey:@"content_Type"]];
        [theObject setContent_Title:[dict objectForKey:@"content_Title"]];
        [theObject setPublisher:[dict objectForKey:@"publisher"]];
        [theObject setContent_Description:[dict objectForKey:@"content_Description"]];
        [theObject setContent_ID:[dict objectForKey:@"content_ID"]];
        [theObject setContent_Source:[dict objectForKey:@"content_Source"]];
        [resultArray addObject:theObject];
        [theObject release];
        theObject=nil;
    NSLog(@"%@", json_string);
これがJSOn文字列の結果です
       ProductivoApp[2087:c203] -JSONValue failed. Error trace is: (
"Error Domain=org.brautaset.JSON.ErrorDomain Code=3 \"Unrecognised leading character\" UserInfo=0x57b5a10 {NSLocalizedDescription=Unrecognised leading character}
URLの私のPHPコード
     $flu=$_POST['searchCode'];
       $query =mysql_query("SELECT * From catalog_Master WHERE category_Title LIKE '%$flu%'");
    $rows = array();
    while($row = mysql_fetch_assoc($query)) {
    $rows[] = $row;
     }