How to Transfer iCloud Data from Old iPhone to New iPhone 6/6s Plus?
Step 1. Make a backup for your old iPhone via iCloud. iCloud will back up your iPhone automatically as long as you turn on iCloud, connect your iDevice to Wi-Fi network and a power source.
Step 2. Turn off your old iPhone. Because it’ll cause conflicts with backups in iCloud.
Step 3. Turn on your iPhone 6/6s (Plus) to set up your iPhone and tap on Restore from iCloud Backup.
Step 4. You’ll see a list of backups. Select the latest backup of your old device and tap Restore, and wait until the device has finished restoring from the iCloud backup.
Step 5. When the restore process is complete, your iPhone will restart.
Note: Restoring from the iTunes or iCloud backup can be a time consuming process and depends on the amount of data contained in the backup and on the speed of your Internet connection.