In iOS 9, some of the best features are the ones that aren't readily visible. iOS 9 has several under-the-hood updates that boost battery life, improve security, and cut down on the amount of storage space iOS updates and apps use on iPhones and iPads.

Even disregarding all of the consumer facing features, these quiet improvements make the upgrade to iOS 9 from iOS 8 or iOS 7 well worth it on all supported devices: the iPhone 4s and up, the iPad 2 and up, and all iPad mini models.

Battery Life

With operating system optimizations, Apple is able to eke out an additional hour of battery life on iPhones under normal usage conditions. One of these improvements, for example, pertains to the iPhone's ambient light and proximity sensor. When the iPhone is placed facedown, it now detects that the screen isn't visible, so an incoming notification does not light up the screen.

batterysettings
There's also a new Low Power Mode on the iPhone that can add another three hours of battery life by cutting down on battery-draining features. Low Power Mode turns off automatic Mail fetch, disables background app refresh, disables motion effects, and disables animated wallpapers.

Low Power mode also throttles the performance of the iPhone so it drains less power. Benchmark testing suggests Low Power mode reduces an iPhone's performance by about 40 percent to cut down on power usage.

Security

iOS 9 prompts users to create 6-digit passcodes instead of 4-digit passcodes for additional security. It's still possible to create a 4-digit passcode, but Apple recommends a 6-digit code because it adds one million possible combinations instead of 10,000, making a passcode harder to crack. Two-factor authentication support is also enhanced in iOS 9.

ios9security

Installation Size

With iOS 9, Apple's cut way down on the installation size, so far less free space is required to download the new update. While iOS required 4.58 GB of space to install, iOS 9 requires only 1.3 GB of space to install, making it more accessible to users who have 16 GB iOS devices.

appdeletionstuff
For devices that still don't have enough space to install the iOS 9 update, Apple has a new auto app delete/reinstall feature. When attempting to install iOS 9 on a device with insufficient space, there's a popup that offers to temporarily delete some apps in order to make room for the update. Apps that are deleted are then reinstalled and replaced after the operating system update is completed.

App Thinning

Apps from third-party developers also require less installation space thanks to a feature called App Thinning. With App Thinning, apps can be optimized for specific devices, allowing them to take up less space on iOS devices.

An app for the iPhone doesn't need all of the iPad assets, so those won't be downloaded. That means faster installs, faster launch times, and more storage space left for other apps and content.

App Thinning also includes on-demand resources like image and sound files, which can be downloaded only when needed. The imagery for later levels in a game, for example, might not be downloaded until it's necessary.

Metal

Apps in iOS 9 take advantage of Metal, making more efficient use of the CPU and GPU for faster scrolling, smoother animations, and better performance. Email, messages, web pages, and PDFs all render faster.

Related Forum: iOS 9

Top Rated Comments

Parasprite Avatar
92 months ago
This is pretty minor, but for devices with a keyboard, they've also added a helpful popup when you hold cmd that shows what keyboard shortcuts you can use.


Not a huge feature, but it's definitely a nice touch.
Score: 12 Votes (Like | Disagree)
nagromme Avatar
92 months ago
...
Why Apple engineers don't design software on less capable devices first and move on from there?
Because then the software will be less capable, and devices newer than the 4S would go to waste.
Score: 10 Votes (Like | Disagree)
elmateo487 Avatar
92 months ago
so much effort required from so many developers (Apple, 3rd party) so that Apple can save $5/device by not moving to 64GB base...
Are you saying app thinning is a bad thing? I shouldn't have to download resources I don't need...
Score: 9 Votes (Like | Disagree)
postpc Avatar
92 months ago
I've been hard on Apple for the last couple of months, but IOS 9 feels brilliant. No Safari crashes so far, and its snappyness has been taken up or notch, everything feels fast and fluent on my dated Ipad 4. Looks like this could be the long awaited Snow Leopard release.
Well done Apple, credit where credit is due.
Score: 8 Votes (Like | Disagree)
TMRJIJ Avatar
92 months ago
iPhone 4S: battery sucks big time (6% lost in almost 5 minutes) and performance without Low power mode enabled is awful!
Why Apple engineers don't design software on less capable devices first and move on from there?
It's the first day and it's indexing. You can complain about it tomorrow but right now we hold your review with a grain of salt.
Score: 8 Votes (Like | Disagree)
cariacou Avatar
92 months ago
so much effort required from so many developers (Apple, 3rd party) so that Apple can save $5/device by not moving to 64GB base...
Score: 7 Votes (Like | Disagree)

Popular Stories

iOS 16

Apple Releases iOS 16.0.2 With Bug Fixes for iPhone 14 Pro Camera Vibration, Copy/Paste Issue and More

Thursday September 22, 2022 1:04 pm PDT by
Apple today released iOS 16.0.2, addressing a number of bugs that iPhone 14 owners have been experiencing since the new devices launched. iOS 16.0.2 comes two weeks after the launch of iOS 16, and it follows iOS 16.0.1, an update made available to iPhone 14 owners on launch day. The update is available for all iPhones that are capable of running iOS 16. The iOS 16.0.2 update can be...
apple watch series 7 aluminum colors yellowbg

Don't Want the Apple Watch Ultra or Series 8? Amazon Has Record Low Prices on Series 7 Models This Week

Friday September 23, 2022 6:56 am PDT by
The Apple Watch Series 8 and Apple Watch Ultra are now available to purchase, but if you aren't interested in these updates you can save a lot of money on Series 7 models right now on Amazon. Note: MacRumors is an affiliate partner with Amazon. When you click a link and make a purchase, we may receive a small payment, which helps us keep the site running. The best deals are on cellular...
Dynamic Island For Android Users Feature

Android App Copying iPhone 14 Pro's Dynamic Island Released on Play Store

Thursday September 22, 2022 7:57 am PDT by
A copycat version of the iPhone 14 Pro's Dynamic Island has arrived on Android's Google Play Store in the form of an app called "dynamicSpot." The app, still in beta, offers customers several different experiences at the top of their smartphones. In its current form, dynamicSpot offers playback control for songs, timers, battery status, and more features coming soon, according to the app's...
maxresdefault

Video Review: Four Days With the iPhone 14 Pro Max

Wednesday September 21, 2022 7:49 am PDT by
Apple on Friday released the new iPhone 14 models, and MacRumors videographer Dan picked one up on launch day. He's been using the iPhone 14 Pro Max non-stop since it came out, and over on the MacRumors YouTube channel, has shared his initial thoughts on the day-to-day experience with the latest iPhone. Subscribe to the MacRumors YouTube channel for more videos. Dan's mini review highlights...
14 vs 16 inch mbp m2 pro and max feature 1

New 14-Inch and 16-Inch MacBook Pros Reportedly Launching Later This Year

Friday September 23, 2022 7:08 am PDT by
Apple plans to release new MacBook Pro models in the fourth quarter of 2022, according to supply chain publication DigiTimes. The report does not mention specific models, but it very likely refers to the next-generation 14-inch and 16-inch MacBook Pros given that the 13-inch model was already updated earlier this year. There has been uncertainty surrounding the timing of new 14-inch and...
facebook meta

Meta Sued Over Tracking iPhone Users Despite Apple's Privacy Features

Thursday September 22, 2022 5:12 am PDT by
Meta is facing a new proposed class action lawsuit that accuses it of tracking and collecting the personal data of iPhone users, despite features and policies made by Apple which are meant to stop that same type of tracking. In August, it was revealed that with the Facebook and Instagram apps, Meta can track all of a user's key taps, keyboard inputs, and more, when using the in-app browser....
AirPods Max 2022 Colors

Ten Things AirPods Pro 2 Tell Us About AirPods Max 2

Saturday September 24, 2022 1:00 am PDT by
Upon the release of the second-generation AirPods Pro, the AirPods Max became the oldest current-generation AirPods product still in Apple's lineup. Introducing several new features like Adaptive Transparency and the H2 chip, the second-generation AirPods Pro may provide some of the best indications yet of what to expect from the second-generation AirPods Max. Almost two years later, rumors...
new airpods pro ear tips

Apple Explains Why Second-Generation AirPods Pro Ear Tips Are Incompatible With Original AirPods Pro

Thursday September 22, 2022 3:12 pm PDT by
Apple today explained why the new silicone ear tips for the second-generation AirPods Pro are not officially compatible with the original AirPods Pro. In an updated support document, Apple said the original AirPods Pro ear tips have "noticeably denser mesh" than the second-generation ear tips. Apple did not provide any additional details, but the mesh density could result in acoustical...
AirPods Pro Second Generation 2 Pairing Feature 1

AirPods Pro 2 Engravings Appear in iOS During Pairing and Connecting

Friday September 23, 2022 9:40 am PDT by
Customers who personalize their second-generation AirPods Pro charging case with an engraving will now have that engraving reflected directly on iOS as they pair and connect their AirPods Pro. Apple allows customers to personalize their AirPods Pro charging case with a special engraving that can include select emojis and Memojis. Unlike before, starting with the second-generation AirPods...