Write at the beginning of a file

I have a fonction who write in a txt file, but at the end of the file, I want a know how to write at the beginning of the file.

this is my fonction:

-(void)ecrireLog:(NSString *) identificateur
{

    NSFileHandle *fichier;
    NSData *data ;
    NSString *chaineLog;



    if ([self creerFichier]) 
    {

        chaineLog = [FonctionUtile concatener:[FonctionUtile dateDuJour] chaine2:@" " chaine3:[FonctionUtile heureCourante] chaine4:@" : "];
        chaineLog = [FonctionUtile concatener:chaineLog chaine2:@" " chaine3:identificateur chaine4:@"\n"];

        data = [chaineLog dataUsingEncoding:NSUTF8StringEncoding];

        fichier = [NSFileHandle fileHandleForUpdatingAtPath:cheminFichier];

        if (fichier == nil)
        {
            NSLog(@"Erreur dans l'ouverture du fichier");
        }
        else 
        {
            [fichier seekToEndO开发者_StackOverflow中文版fFile];

            [fichier writeData: data];
        }

        [fichier closeFile];
    }
}

thx

Somehow I think this is a trick question.

Don't call seekToEndOfFile?

What if you loaded the text file into an NSString, then created a new NSString with whatever text you want in the beginning, then concatenated the two strings together and saved as a text file? Seems simple enough.