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
108 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
108 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
108 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
108 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
108 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
108 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 4 Web Push

Apple Confirms Governments Using Push Notifications to Surveil Users

Wednesday December 6, 2023 5:06 am PST by
Unidentified governments are surveilling smartphone users by tracking push notifications that move through Google's and Apple's servers, a US senator warned on Wednesday (via Reuters). In a letter to the Department of Justice, Senator Ron Wyden said foreign officials were demanding the data from the tech giants to track smartphones. The traffic flowing from apps that send push notifications...
iOS 17

iOS 17.2 Will Add These 12 New Features to Your iPhone

Friday December 1, 2023 12:19 pm PST by
iOS 17.2 has been in beta testing for over a month, and it should be released to all users in a few more weeks. The software update includes many new features and changes for iPhones, including the dozen that we have highlighted below. iOS 17.2 is expected to be released to the public in mid-December. To learn about even more features coming in the update, check out our full list. Journal ...
iphone se 4 modified flag edges

iPhone SE 4 May Reuse Existing iPhone 14 Battery

Wednesday December 6, 2023 1:17 pm PST by
Recently, MacRumors has received details on the battery currently being tested on the upcoming fourth-generation iPhone SE, and the information corroborates previous findings in relation to the device. The iPhone SE 4, known by its device identifier D59, is expected to use the exact same battery found in the base model iPhone 14. Partially assembled prototypes of the next iPhone SE have been ...
best buy snowflakes

Best Buy's New Weekend Sale Has Record Low Prices on MacBook Pro and MacBook Air

Friday December 8, 2023 7:37 am PST by
Best Buy's month-long holiday sale continues this weekend with multiple all-time low prices on Apple's line of MacBook Pro and MacBook Air computers. In addition to Apple notebooks, Best Buy's event has discounts sitewide on home appliances, TVs, video games, and more. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive...
beeper mini

Apple Puts a Stop to Beeper Mini's iMessage for Android Feature

Friday December 8, 2023 2:24 pm PST by
Apple appears to have closed the loophole that Beeper Mini used to bring iMessage to Android, putting a stop to blue bubbles from Android devices. Beeper Mini quit working earlier today, with users receiving "failed to lookup on server: lookup request timed out" error messages. Beeper said on Twitter that it is investigating the issue, but Beeper CEO Eric Migicovsky told TechCrunch that "all ...
maxresdefault

Review: Two Months With the iPhone 15 Pro Max

Thursday December 7, 2023 12:04 pm PST by
Apple's iPhone 15 lineup came out in September, and while most reviews are done shortly after a new device launches, we like to follow up with a longer term review that gives us an opportunity to provide a deeper dive into what it's like using these phones on a day to day basis for months. Subscribe to the MacRumors YouTube channel for more videos. MacRumors videographer Dan Barbera has been...
12

Apple to Launch Two iPad Air and Two OLED iPad Pro Models Early Next Year

Wednesday December 6, 2023 9:53 am PST by
To boost falling iPad sales, Apple has a major refresh planned for the iPad lineup in early 2024, according to Bloomberg's Mark Gurman. Apple plans to debut new iPad Air and iPad Pro models, both of which will feature notable changes. The iPad Air will come in two sizes like the iPad Pro for the first time. The smaller model will continue to measure in at 10.9 inches, but the larger version...
anker new gold

Anker Begins Countdown to Christmas Sale With Up to 50% Off Popular Charging Accessories

Thursday December 7, 2023 7:55 am PST by
Anker has launched its newest holiday sale, this one offering a special deal every day in the lead-up to Christmas. These sales offer up to 50 percent off select products, and include discounts on USB-C chargers, portable batteries, and much more. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive a small payment, which ...