1) See Which Apps Are Messing With Your Battery
While you've been able to see just which apps consume a lot of your battery,
you can now also find out how long you actually stared at and used each app.
2) Draw on Photos
Available only in Mail, you can attach a photo and do several actions with it
just by by pressing down on it and choosing "Markup."
You can draw in different colors, add a signature, place a text box, and magnify a certain part of your photo.
3) Change Over to Cell Service Without Doing Anything
Losing WiFi is annoying, but having to turn it off before your phone connects to a cellular network is more annoying
— not anymore though.
WiFi Assist, which is automatically turned on when you download iOS 9, will do this feature for you.
4) Easily Select More Than One Photo
Instead of having to tap on every single photo, you can simply press Select and
drag your finger across as many photos as you want.
5) Use "Hey Siri" Now Unplugged
If you're hands are occupied, you can now set up the "Hey Siri" function and use Siri hands-free,
without being connected to a power source.
6) Leave a Message on FaceTimeIt's not a video message, but you do get the option to send a message to a friend who's missed your FaceTime call.
7) Hide Your Photos in Camera RollAnother new folder comes to Photos, specifically so you can hide private photos from your regular Camera Roll
during all those times someone goes through your phone.
To hide a photo, just tap on a photo in your Camera Roll, click the share button, and at the bottom you'll see a Hide button.
8) Get Audio SuggestionsNow, when you plug in your headphones, an app will appear that will suggest some sort of audio usage — like Music.