Read next: The iOS 9 review.

Swipe right for Siri? Old news. Here are several iOS 9 features you might not have discovered yet — or ones that you'll find surprisingly useful.

Phone Number Lookup

In iOS 9, your iPhone can pull data from the native Mail app to suggest who might be calling when an unknown call comes in. The same works for outgoing calls: the other day I dug around in my email to find a phone number for someone who wasn't in my Contacts, and later on noticed in the outgoing call log that the phone had correctly identified who the person was with a "Maybe" in front of her name.

Settings search in iOS 9

Searching Settings

The settings menu on iOS has always been a chore to navigate, but with iOS 9 you finally won't have to suffer through three, four, or five taps just to do something simple like manage your location services. One quick swipe down from the top of the settings menu lets you search for any one of the myriad settings that are typically buried, meaning you can get back to texting or scrolling through Twitter faster than ever.

In-app search

Apple's built-in search tool (née Spotlight), which you can access by swiping down from any home screen or at the top of the new Siri screen, has gotten a bunch of new features for iOS 9. The most significant one is the ability to search within third-party apps, making it much easier to find content than ever before. Once an app has been updated to support iOS 9's search function, you can just quickly type in searches from almost anywhere and the in-app results will display alongside Apple's standard web search results. A number of apps, such as Outlook and Dropbox, have already been updated to support the feature, and we expect that many more will soon follow.

Wi-Fi Assist

Just because you're within range of a free Wi-Fi hotspot doesn't mean you want its crummy connection stalling your mission-critical Google Maps search. Now your phone will ignore Wi-Fi connections that are slowing you down and will fall back to cellular. It's on by default, too!

Low-power mode

Yes, some Android phones have it, and you could always, say, turn off Wi-Fi or do other manual things on an iPhone, to extend battery life. But this is intelligent. It gives you more battery life by doing things like halting background refreshing of apps, and cutting off animations. But the phone still performs all its key functions. That is key.

Low power mode in iOS 9

See what's killing your battery

Even if you haven't hit that critical 10 percent point, you can get an idea of what's draining your phone in battery settings. The best part is you can tap the little clock icon at the top of the list. That toggles more information, including screen-time and background time for the app. So, yes, TwoDots is using all your power, but that's normal because it's on the screen all the time. But maybe another app is draining life even though it's just in the background (Hey Inbox, how you doing?), and you might consider switching it out for something less thirsty for power.

Yes, you can bring back the all-cap keyboard

The greatest feature in iOS 9 is the mixed-case keyboard introduced for the first time in the iPhone's history. But if you find that distracting, if you want to return to the days of moving your thumb out of the way to decipher the state of the shift key (which is now slightly improved) then be comforted in the fact that you can, even if you shouldn't. Settings: General: Accessibility: Keyboard. You can even turn off the key popups under Settings: General: Keyboard: Character Preview.

View all your selfies or screenshots at once

If you head into Photos, you'll find two new sections: selfies and screenshots. That selfies folder will probably be a lot of fun to browse through, but it's the screenshots section that's going to be most important for the tech obsessives. No longer will you have to hunt through your entire photo stream to find and delete accidental or old screenshots. Just pop in, swipe across all of them — another new photos feature — and delete. No more mess.

Headphone smarts

Plug your favorite pair of headphones or earbuds in, and you’ll notice a new icon at the lower left of your iPhone / iPad lock screen. iOS 9 now understands that the presence of headphones probably means you want to listen to music, so it’ll automatically suggest the app you’ve used most recently. And best of all, no one’s forcing Apple Music on you; this also works for Spotify and other music services.

iOS 9's new Notes app

Double-tap for Apple Pay

Before, there wasn't a physical button dedicated to Apple Pay (like there is on Apple Watch). In iOS 9, you can simply double tap the home button — no passcode or fingerprint recognition required — and you'll jump immediately into Passbook with the Apple Pay prompt ready to go. Of course, you'll need your fingerprint to finalize the payment, but this should make it a little less annoying to pay with your iPhone. If this seems like an unwanted security risk, you can also turn it off in the Settings panel under Wallet & Apple Pay.

A Notes app that's actually useful

Apple's native I-should-write-that-down-before-I-forget solution has always been fairly barebones. The updates to iOS 9 won't replace Evernote, but the addition of some basic sketch tools (think: first-gen Paper app) is actually pretty great and intuitive for quick sketches. There's even a ruler for helping you draw straight lines.

Any others? Leave them in the comments below.