public void ManipulatePdf(String dest)
{
PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));
PdfAcroForm form = PdfAcroForm.GetAcroForm(pdfDoc, true);
IDictionary <String, PdfFormField> fields = form.GetFormFields();
PdfFormField checkedField = fields[CHECKED_FIELD_NAME];
PdfFormField uncheckedField = fields[UNCHECKED_FIELD_NAME];
// Get array of possible values of the checkbox
String[] states = checkedField.GetAppearanceStates();
// See all possible values in the console
foreach (String state in states)
{
Console.Write(state + "; ");
}
// Search and set checked state to the previously unchecked checkbox and vice versa
foreach (String state in states)
{
if (state.Equals(CHECKED_STATE_VALUE))
{
uncheckedField.SetValue(state);
}
else if (state.Equals(UNCHECKED_STATE_VALUE))
{
checkedField.SetValue(state);
}
}
pdfDoc.Close();
}