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
111 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
111 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
111 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
111 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
111 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
111 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

reset password request iphone

Warning: Apple Users Targeted in Phishing Attack Involving Rapid Password Reset Requests

Tuesday March 26, 2024 4:34 pm PDT by
Phishing attacks taking advantage of Apple's password reset feature have become increasingly common, according to a report from KrebsOnSecurity. Multiple Apple users have been targeted in an attack that bombards them with an endless stream of notifications or multi-factor authentication (MFA) messages in an attempt to cause panic so they'll respond favorably to social engineering. An...
iPhone Home Screen Gradient Blank Spaces 1

Sources: iOS 18 Lets Apps Be Placed Anywhere on Home Screen Grid

Sunday March 24, 2024 1:33 pm PDT by
iOS 18 will give iPhone users greater control over Home Screen app icon arrangement, according to sources familiar with the matter. While app icons will likely remain locked to an invisible grid system on the Home Screen, to ensure there is some uniformity, our sources say that users will be able to arrange icons more freely on iOS 18. For example, we expect that the update will introduce...
Generic iOS 18 Feature Purple

iOS 18: What to Expect From 'Biggest' Update in iPhone's History

Wednesday March 27, 2024 11:10 am PDT by
At least some Apple software engineers continue to believe that iOS 18 will be the "biggest" update in the iPhone's history, according to Bloomberg's Mark Gurman. Below, we recap rumored features and changes for the iPhone. "The iOS 18 update is expected to be the most ambitious overhaul of the iPhone's software in its history, according to people working on the upgrade," wrote Gurman, in a r...
maxresdefault

Apple Announces WWDC 2024 Event for June 10 to 14

Tuesday March 26, 2024 10:02 am PDT by
Apple today announced that its 35th annual Worldwide Developers Conference is set to take place from Monday, June 10 to Friday, June 14. As with WWDC events since 2020, WWDC 2024 will be an online event that is open to all developers at no cost. Subscribe to the MacRumors YouTube channel for more videos. WWDC 2024 will include online sessions and labs so that developers can learn about new...
apple maps 3d feature

Apple Maps May Gain Custom Routes With iOS 18

Tuesday March 26, 2024 3:10 pm PDT by
Apple may be planning to add support for "custom routes" in Apple Maps in iOS 18, according to code reviewed by MacRumors. Apple Maps does not currently offer a way to input self-selected routes, with Maps users limited to Apple's pre-selected options, but that may change in iOS 18. Apple has pushed an iOS 18 file to its maps backend labeled "CustomRouteCreation." While not much is revealed...
iPad Pro 2024 Landscape Camera Feature

New iPad Pro Again Rumored to Feature Landscape Front-Facing Camera

Monday March 25, 2024 5:43 am PDT by
The next-generation iPad Pro will feature a landscape-oriented front-facing camera for the first time, according to the Apple leaker known as "Instant Digital." Instant Digital reiterated the design change earlier today on Weibo with a simple accompanying 2D image. The post reveals that the entire TrueDepth camera array will move to the right side of the device, while the microphone will...
sonoma desktop wwdc

Apple Releases macOS Sonoma 14.4.1 With Fix for USB Hub Bug

Monday March 25, 2024 10:10 am PDT by
Apple today released macOS Sonoma 14.4.1, a minor update for the macOS Sonoma operating system that launched last September. macOS Sonoma 14.4.1 comes three weeks after macOS Sonoma 14.4. The ‌‌‌‌macOS Sonoma‌‌ 14.4‌.1 update can be downloaded for free on all eligible Macs using the Software Update section of System Settings. There's also a macOS 13.6.6 release for those who...
Generic iOS 18 Feature Purple

iOS 18 Will Finally Bring This Android Feature to iPhone

Monday March 25, 2024 6:42 am PDT by
iOS 18 will allow iPhone users to place app icons anywhere on the Home Screen grid, according to sources familiar with development of the software update. This basic feature has long been available on Android smartphones. While app icons will likely remain locked to an invisible grid system on the Home Screen, our sources said that users will be able to arrange icons more freely on iOS 18....