Using iTunes:

NOTE: With iTunes installed on a computer you can transfer the contacts stored on your iPhone to a Google account. Afterwards you can sync the contacts from the account with the HTC One M9. To do so:

1. Open iTunes on your computer
2. Connect the iPhone via USB
3. After connected, the iPhone will pop-up in iTunes
4. Access the phone's summary page and click the "Info" tab
5. Check the "Sync Contacts With" box
6. Select "Google Contacts" from the drop-down menu
7. Sign in with your Google account. Alternatively, click "Configure" and select an account from the list
8. Click "Apply"
9. Once the contacts have been synced with the Google account, register it to the One M9 and allow it to sync contacts with your phone

Using iCloud:

NOTE: If you have used the iCloud backup service on your iPhone in the past, your contacts should already be backed up on your iCloud account. You can access it using a computer with Internet, and export these contacts for use on Android

1. Open the Internet browser on your computer
2. Visit https://www.icloud.com/
3. Log in with your iCloud account
4. Go to the "Contacts" section and mark the boxes next to the contacts you wish to share
5. Click "Settings" > "Export vCard"
6. Once the vCard file is exported to the computer, import it to "Google Contacts". (Alternatively, skip this step and instead follow the next one)
7. Connect the One M9 to your computer via USB and copy the vCard file to the phone. Launch "People" and tap "Menu" > "Manage Contacts" > "Import / Export contacts" and choose to import it from the storage

Via "My Contacts Backup":

NOTE: The methods above require access to a computer but you can easily transfer your contacts using third party apps. My Contacts Backup is an iOS app that allows you to back up and transfer contacts via email.

1. Access the App Store and install "My Contacts Backup" on your iPhone
2. Launch the app and tap "Backup" (this will back up your contacts in a VCF file)
3. After the backup file is done, tap "Email"
4. Compose a new email containing the attached backup file
5. Send the email to your own address
6. Switch to the HTC One M9 and open the email
7. Download the attached file and import it to your phonebook using the "People" app

Using "Send Anywhere":

NOTE: Send Anywhere is another third party app for both iOS and Android, which allows you to share contacts and other types of files without needing a computer, over a peer-to-peer connection. To do so:

1. Install "Send Anywhere" on the HTC One M9 via the Google Play Store
2. Install the same application on the iPhone via the App Store
3. Launch the app on both smartphones
4. On the iPhone, tap "Send" > "Contacts"
5. Mark the contacts you want to transfer
6. Lastly, select the desired method of transfer. Tapping "Receive" on the HTC One M9 allows you to manually enter the transfer code generated on the iPhone. Otherwise you can tap "Generate QR Code" on the iPhone and scan the code with the iPhone's camera to commence the contact transfer