Match the symptom to the next check
| What you see | Likely cause | What to do next |
|---|---|---|
| The PDF opens in Mail or a browser, but there is no signature tool | You are looking at a limited preview | Save the attachment to Files, then open the saved PDF in Preview or Markup. |
| The file asks for a password before it opens | It has an open password | Get the password from the sender. You cannot sign a file you cannot open. |
| The PDF opens, but editing or signing is disabled | The owner restricted changes | Ask the owner for permission or an unrestricted signing copy. |
| The document says it is certified or already digitally signed | Changes may invalidate an existing digital signature | Use the required signing workflow or request an unsigned copy. |
| The signature appears, but is gone when you reopen the file | The change was not committed or you opened a different copy | Tap Done or export, then reopen that exact saved file before sending it. |
Step by step
- 01
Save the real attachment to Files
A message or browser preview may expose fewer controls than the saved document. Use Share, choose Save to Files, give the copy a clear name, and open that file.
- 02
Try Apple’s built-in route first
For an ordinary unprotected PDF, Preview or Markup can add a finger-drawn signature. If that is all you need, there is no reason to add another app.
- 03
Separate a scanned page from a locked file
A scan is usually a flat page image; you can still place a visible signature over it. A locked PDF uses security permissions that may prevent any change.
- 04
Respect passwords and existing certification
Do not bypass a password or alter a certified PDF. Ask the sender for the password, a signable version, or the signing portal they expect you to use.
- 05
Choose the signature method
If finger drawing is acceptable, use Markup. If the unprotected document accepts a visible image-based signature and you want the handwriting you use on paper, capture and clean that signature first.
- 06
Reopen the finished copy
After tapping Done or exporting, close the viewer and open the exact saved file. Check the correct page, signature position, and filename before you attach it to a reply.
PDF SIGN & SCAN
Your real signature, ready when the PDF arrives.
Scan it once. Place it carefully. Send the signed copy from your iPhone.
App StoreAvoid the fixes that create a worse document
- Do not sign a screenshot when the recipient expects a complete multi-page PDF.
- Do not flatten or re-save a certificate-signed PDF unless the document owner approves that change.
- Keep the original and the finished copy under different filenames.
Questions
Why is the signature button missing on my iPhone?
You may be viewing the attachment inside an app that offers only a preview. Save the PDF to Files and open the saved copy in Preview or Markup.
Can I sign a read-only PDF on iPhone?
Not if its security settings prohibit changes. Ask the sender for a signable copy or permission rather than trying to remove restrictions.
Can I sign a scanned PDF?
Often yes. A scanned page does not need a fillable signature field for a visible signature to be placed on it, provided the PDF itself permits changes.
Does a missing signature field mean the PDF cannot be signed?
Not necessarily. A visible electronic signature can be placed on an ordinary PDF without an interactive field, but certificate-based workflows may require a prepared field or a specific service.