Updated Feb 22,2019 | by Joy
Sometimes, people prefer to create PDF files on iPhone for their business purpose and share them with co-worker via email. These files always contain some confidential information like personal forms and contract, so it’s quite important to password protect a PDF file on iPhone.

Sadly, there is no built-in feature on iOS device enabling users to make an encrypted PDF file. Don’t worry. In this article, we will show you a detailed guide on how to password protect a PDF on iPhone with third-party tool.
How to Password Protect a PDF on iPhone with Third-Party Tool
There are numerous third-party apps that can allow you to complete the PDF encryption on iOS device with your unique password, like Scanbot Pro ($6.99) and Genius Scan+ ($13.99). Today we will take Foxit MobilePDF as an example. It comes with a 7-day free trial and then you can upgrade to its pro version with $10.99 or $14.99 after the trial ends. Follow the steps below.
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Note that there is no free way to lock your PDF file on iOS device as most good iOS applications are paid anyway.
Step 1. Open your iPhone and search for Foxit MobilePDF in App Store. Simply download and install it on your device.

Step 2. Launch this app on your iPhone. You are required to agree to the terms and conditions by clicking “ACCEPT & CONTINUE” icon at the bottom of the page.
After that, it’s optional to sign in using your Email ID and password in the popup window or just tap on the “X” close button in the top left corner.
Step 3. Click the menu button in the top left corner and then go to “Cloud” > “iCloud Drive”. Then your PDF file and other documents will be displayed in this page.

Step 4. Just choose the PDF file you want to encrypt on iPhone. Tap on the more button (which is labeled with three dots) at the top right and click “File Encryption”.

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You will receive a popup window saying that this is an advanced feature. Just click “7-day Free Trial” icon to continue encrypting a PDF file on iPhone.

Step 5. After that, there are two security options for you to password protect a PDF on iPhone, including “Open Document” and “Add Document Restrictions”. Let me respectively explain how they work.
Open Document: When this option is turned on, password is required to open your PDF file.
Add Document Restrictions: If you choose this option, password is required to allow some specific action like print, fill form, manage pages, edit, extract content, etc. Just turn on or turn off the switch next to each option you want to allow or restrict.
After selecting your target option, enter your own password and tap on “Done” at the top right of the screen. Then you can click the share button at the top to save the file or email it to anyone. When you open the file next time, it will ask for password for viewing or editing, printing, etc.
Bonus Tip: How to Wirelessly Transfer PDF to iPhone after Encrypting PDF Online
Considering that you don’t want to upgrade the app to its pro version after the trial ends, you can try to encrypt a PDF file online and then transfer PDF to iPhone. To easily complete the encryption online, just try to use SodaPDF and follow the simple guide in its homepage. Here I mainly talk about the steps of transferring your PDF to iPhone wirelessly.
IOTransfer is an easy tool enabling you to wirelessly transfer videos, photos, files, etc. from computer to iPhone without the need to fetch your USB cable. Follow the steps below.
Step 1. Free download IOTransfer and install it to your computer running Windows 7/8/8.1/10.
Step 2. Search for “AirTrans” app in App Store on your iPhone and install it on your device. Then open it.
Step 3. Launch IOTransfer on your computer. Click “AIR-TRANS” at the top and then tap on “Start Transfer” at the bottom. Then IOTransfer will automatically search for available iOS device or you can scan the QR code with AirTrans app on your iPhone.

Step 4. Drag your PDF file into the blank page and click “Send to iPhone” to start the transfer. Then you can view the file in AirTrans app on your iPhone.

Watch a video tutorial on how to transfer files between iPhone and PC wirelessly
Bottom Line:
Hope the article can help you easily password protect a PDF on iPhone. If you have any question or other good idea, leave us a comment below.
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