QStandardPaths::PicturesLocation invalid on iOS

QStandardPaths::writableLocation(QStandardPaths::PicturesLocation);

return a non empty path on iOS, but that is not writable, nor can one create the path.

some test code below to past into hello world:

QString _savePath = QStandardPaths::writableLocation(QStandardPaths::PicturesLocation);

QDir dir(_savePath);
if (!dir.exists()) {
if (!dir.mkpath(_savePath))

{ qDebug() << "can't make" << _savePath; }

}
QFile f(_savePath+"/test.tmp");
if (f.open(QIODevice::WriteOnly))

{ f.write("does this work on iOS?"); f.close(); }