无法在pdf中呈现Č字符

Question

预期产出：

Čairo

现实：

airo

我正在初始化字体：

        Dim cb As PdfContentByte = writer.DirectContent

        cb.BeginText()
        Dim bf As BaseFont
        bf = BaseFont.CreateFont("c:\windows\fonts\arial.ttf", BaseFont.IDENTITY_H, BaseFont.EMBEDDED)

我也试过这样做：

            Dim f As New Font(iTextSharp.text.Font.FontFamily.HELVETICA, 10.0F, iTextSharp.text.Font.NORMAL, BaseColor.BLACK)
            Dim ph As New Phrase(moderate_foods(i), f)
            Dim cell As New PdfPCell(ph)

我们如何在pdf中呈现Č字符？