The early indications are that iOS 9 has been adopted more quickly than any version of the mobile OS that came before it. If you're one of the millions of people who've installed the software on your iPhone, iPod touch or iPad, here are some essential features and tricks you should be aware of for getting the most out of your Apple device.

Turn on the low power mode

For iPhones, iOS 9 brings with it a brand new low power mode designed to shut down some background apps and processes and extend the life of your device's battery. You get the option to automatically enable it when battery life reaches 20 percent, but you can also switch it on manually via the Battery entry in the Settings app.

Hide photos from view

iOS 9 comes with a number of new photo tricks, including the ability to hide images you don't want to see (or you don't want others to see). With one or more pictures selected, you'll see a Hide option on the Share menu.

Just note these photos are still visible via the Albums view inside the app (and you can opt to unhide them from here too).

Find your friends more easily

The Find My Friends app isn't a new one but Apple has made it a mandatory stock app for the first time and added a Notification Center widget as well.

To activate it in Notification Center, drag down from the top of the screen to bring up the Today page, then tap Edit to add the widget. When it appears, select Find Friends to choose which of your iCloud contacts you want to add.

Add any kind of attachment

When iOS updates, so do all of Apple's built-in apps. In the upgraded Mail app you can now double-tap inside an email to add any kind of file as an attachment (rather than just a photo or video) – scroll right to find the Add Attachment option. Tap Locations if the file you want to add isn't in iCloud (Dropbox and Google Drive are also supported).

Split the screen

If you're on a 2013 iPad or newer, swipe in from the right to bring in a sidebar you can fill with another app (a new feature called Slide Over). iPad Air 2 and iPad Pro users can also drag the separator line to the center for a full multitasking experience called Split View. It's mostly Apple's own apps that support the feature right now, but third-party Slide Over and Split View updates are already trickling in.

Use picture-in-picture

Here's another tip that's only for iPad users (2013 models or later): picture-in-picture video. When using an app that's been updated to use the feature (like Pocket or Hulu) you can tap the picture-in-picture icon in the lower right corner of a playing video, then move or resize the window accordingly. Tap on the Home button on your iPad to then switch to another app.

Get public transit directions

Apple Maps has been given an update with iOS 9 and now supports public transit directions at last – you'll even get an update if your bus is late. The only problem is only a handful of cities across the world support it at the moment. If your area is one of them then the transit option appears alongside driving and walking when you search for directions.

Ditch dodgy Wi-Fi networks

If you're using an iPhone running iOS 9 you can take advantage of a very useful new feature called Wi-Fi Assist. When enabled (through the Mobile Data or Cellular menu in Settings), iOS will quickly switch to a speedy 4G cellular network (if available) should you find yourself stuck on a slow Wi-Fi one. Just make sure your data plan can handle it.

Turn your iPad keyboard into a trackpad

Another iOS 9 tip that's only for iPad owners, that's also the closest iOS has ever gotten to mouse support.

If you tap and hold with two fingers on the keyboard, it automatically turns into a trackpad. You can then move your fingers around to more easily select text or move the cursor to do whatever it is you're trying to do on your tablet. Lift up your fingers from the screen again and the keyboard returns to normal.

Find settings more easily

There are all kinds of configuration options hidden away in the iOS Settings app but sometimes it's not particularly easy to work out where the option you need is. Apple has solved the problem by making the Settings app searchable. Use the search box that appears at the top of the main page and type out whatever setting you're looking for.

Call Siri from anywhere

On iOS 8 you could say "hey Siri" to bring up Apple's digital voice assistant, but only if the phone was plugged in and charging. Now you can call the app up anytime, as long as you have an iPhone 6S or iPhone 6S Plus. Head to the Settings app, open up the General page and tap Siri to find the option. You'll then be asked to teach Siri the sound of your voice.

Block out the ads

Somewhat controversially (due to its providing ad-supported content minus the support), iOS 9 adds ad-blocking to Safari, so you can strip out pop-ups and the like on the web. First you need to install an ad-blocker and then you can choose it in the Safari section of Settings.

Most ad-blockers let you customize the browsing experience further with their own set of options, including white-listing sites you want to continue to support.

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