IOS : right way to append data to a user selected file

MacOSX and iOS
1

Dear all

It’s an ios specific question. i want my user to select an existing text file with ios native file chooser and then to append a text at the end of it.
In ios I use the “open” file browser (native version) as in the demo. I get the file url and then get the corresponding File object (“resultfile” in the following code).

I try to create an FileOutputStream but output.openedOk() always return False…

I can’t understand why… Any idea ? is it a problem with iOS file manegement/protection ?

Thanks in advance for any hint !

if (result.isLocalFile()){
auto resultfile=result.getLocalFile();
// bool success =resultfile.appendText(“TEST APPEND”);
FileOutputStream output (resultfile);
if (output.openedOk())
{
bool success = output.writeText(“TESTString”, false, false, “\r\n”);
output.flush();

                if (success){
                    AlertWindow::showMessageBoxAsync (AlertWindow::InfoIcon,
                                                      "File Chooser...",
                                                      "appended");
                } else {
                    AlertWindow::showMessageBoxAsync (AlertWindow::InfoIcon,
                                                      "File Chooser...",
                                                      "append error");
                }
            } else {
                AlertWindow::showMessageBoxAsync (AlertWindow::InfoIcon,
                                                                         "File Chooser...",
                                                                         "Can't open");
            }
        }