Review: iOS 9 delivers polish and stability

Over the last couple of years, iOS has rightfully come under criticism for being less than rock-solid stable. This year's version appears to be aimed at offering better performance, increased stability and a more predictive user experience in which the operating system tries to anticipate user needs.

In addition, iOS 9 is packed with refinements and new features that try to anticipate and volunteer useful information to users based on what they're doing, along with under-the-hood optimizations that should give iPhone users additional battery life. iPad users, especially those with newer iPads, should consider iOS 9 a must-have update, as it unlocks multitasking features that power users have wanted.

iOS 9 is the third version of iOS to feature 64-bit code; it supports Apple devices dating back to the iPhone 4S, all versions of the iPad mini and all iPads since the iPad 2. It also runs on the fifth and sixth generation iPod Touch.

For this review, I tested iOS 9 on an iPhone 6, an iPhone 5, an iPad mini and an iPad Air 2, with the bulk of my focus on the iPhone 6.

Installation

As always, before installing this update, go to Settings / iCloud / Storage & Backup and tap Backup Now. Or plug the device into your computer and click Back Up in iTunes. Be patient and wait for the backup to complete because you will want a full backup of your data in case something goes awry with the update. I didn't run into any problems updating my iPhone or iPads, but the old adage still holds true: Better safe than sorry.

Once the backup is done, update your iPhone by navigating to Settings / General / Software Update. For this, you will need a Wi-Fi connection and at least 50% battery life, or else the device will have to be plugged in.

Last year's rollout required over 4.5GB of available storage for the update to work. That resulted in many unhappy users who couldn't update wirelessly, especially those running devices with only 16GB of storage. This year, iOS 9 can be installed via Wi-Fi as long as there is at least 1.3GB of space, a far more reasonable requirement. Apple applied a few tricks to make this happen, including streaming updates that don't need additional space to be unpacked and only downloading those assets necessary for the device that is being updated.

If more room is needed, Apple crafted a workaround called automatic app deletions that temporarily deletes larger apps while preserving user-specific data. After the update is complete, any deleted app is automatically restored. There's also a new option to put off the update until a time when the iPhone is idle.

When you update via Wi-Fi, all of your settings, media, data and apps are left intact, but the update may take some time; potentially several hours depending on the size of the download. If time is of the essence, there's another way. Plug the device into a PC or Mac running iTunes and use the option to either Restore or Upgrade. With the Upgrade option, your settings, data, media and apps are left in place. With the Restore option, everything on the device is deleted before a fresh version of the operating system is installed. If you've been having issues with your device, or if you've modified the OS in ways Apple hasn't sanctioned, a Restore may be your only bet.

Once the upgrade is complete and your device rebooted, Apple's Setup Assistant will guide you through the process of connecting to a Wi-Fi network, enabling Location Services and tweaking some other options. If you chose to perform a Restore, there are options to set your device up as new or to restore from a backup stored on iCloud or iTunes.

Starting up

After a few swipes, a couple of password entries and a reboot or two, iOS 9 leaves you at the Home Screen, which looks pretty much as it did before. As with iOS 8, the interface theme is still built around a bright and colorful palette; navigating the operating system is still designed around the concept of layers, where tapping apps and folders zooms in and out of virtual 3D planes; the frosted white interface elements are still influenced by the colors of the current wallpaper; and the parallax effect (in which app and folder icons slightly shift depending on how the device is held) remains.

There are a few new features, such as the revamped Search screens, which can be accessed from the Home Screen by swiping either down for a quick search or left to right for a more detailed view. But iOS 9's most important aspects revolve around refining the technology that was already present.

Better performance, more storage

The built-in iOS apps have all been rewritten to take advantage of Metal, Apple's API that was designed to utilize graphics more efficiently and effectively. Metal takes the best bits of OpenGL and OpenCL and combines them to provide low-overhead access to the GPU for both graphics and data processing.

The result is that iOS 9 feels very fluid and responsive: Animations for zooming in and out of apps and folders, scrolling through lists and using the multitasking view to switch between apps are all smooth and devoid of any stutter. Interestingly, the only system app I encountered that still dropped frames while scrolling is the new News app (which replaces the Newstand app). Also, third-party apps will need to be updated to take advantage of Metal.

iOS 9 is also optimized for better energy and storage conservation. According to Apple, iOS 9 users can gain up to an hour more of battery life on a full charge via facedown detection (which leaves the screen off when a notification is received and the phone is lying on its display), optimized backlight algorithms, adaptive sleep delays and a more efficient low-power idle state.

To manually conserve energy, there is a new preference under Settings called Battery that has the option to enable Low Power Mode. This new setting scales back some features such as background app data refresh; throttles the GPU and CPU from entering the most power-hungry processing states; and disables animations and some of the more taxing visual effects.

Despite these newfound efficiencies, the device didn't feel slow when I used it in Low Power Mode (the battery indicator turns yellow when the mode is active). You can turn on the Low Power Mode manually or have it automatically enabled when the iPhone pops up a low battery warning at the 20% or 10% charge marks. Once the phone is charging, it will automatically switch back to normal operations when the battery is full or near full.

Enhancing storage

There are several ways Apple has worked to improve storage, including the use an optimization technique called App Thinning.

App Thinning has three components: App Slicing, On-Demand Resources and Bitcode.

App Slicing: There’s a reason a single app can run on an iPhone, iPad and iPhone touch, and that is because each app can contain different sets of code that execute depending on the device. Some of these include: 32/64-bit code, images scaled for Retina- and non-Retina displays, and snippets of code that are specific to low- and high-power GPU modes. Even if that code is not needed by the individual device, it still resides in the app, taking up storage. With App Slicing, the App Store only delivers what's required for each device. That means no more unnecessary code being bundled and downloaded, saving space and reducing download size.

One note on App Slicing: iOS 9 allows developers to create 64-bit-only apps. Since iOS 9 runs on devices that are not 64-bit capable (such as the fifth-generation iPod Touch; the iPhone 4S, 5 and 5C; the first-generation iPad mini; and iPads 2 through 4), those 64-bit-only apps won't even display in the App Store on unsupported devices.

On-Demand Resources: In iOS 9, the App Store can retain separate app resources so that some segments are only delivered as needed. Think of a video game: When a player is on Level 1, the game doesn't require any other level data except what's being used; when Level 2 is required, it's downloaded, and Level 1 is deleted. iOS reclaims that space on the fly.

Bitcode: This is a new technology that, when applied, allows the App Store to recompile an app to its updated specs before it is downloaded to a device. Bitcode offers the potential benefits of automatically including improvements Apple engineers have made to the app's compiler. This means that if ever Apple decides to switch chip architectures or support new devices, developers won't have to resubmit their apps with updated code; Bitcode-enabled apps will automatically receive that support. (For now, this is optional for iOS 9 apps, but a requirement for watchOS 2 submissions.)

Search and Siri

iOS 9 aims to please by trying to make frequently accessed data readily available, and in some cases -- such as when entering a vehicle or while providing directions in GPS mode --- volunteering information ahead of time.

A left-to-right swipe from the Home Screen brings up the new Search area, which is separated into three sections: Siri Suggestions (which displays the last four contacts and the last four apps used); Nearby (which offers shortcuts to local points of interest, such as restaurants, bars, convenience stores and nightlife destinations); and News (which provides a list of local headlines and article snippets).

If four isn't enough for you, the Siri Suggestions and News sections have toggles for displaying more results. Pressing Show More displays the last eight contacts, the last eight apps, and the eight latest trending news topics.

In Siri Suggestions, tapping a contact's avatar slides several methods of communication into view: telephone, messaging, FaceTime, and a shortcut to the contact card. Tapping on an app or News headline opens the respective app, as you'd expect. Tapping a point-of-interest category launches Maps, which then displays your location on a map, with pin drops representing locations for search results. The map is positioned over a text-based list of search results, which shows more information about the results, including Yelp data ratings, number of reviews, whether a location is open/closed and a picture/avatar representing the establishment.

Considering the convenience of the new Search screen, I'm surprised there isn't an option to make it the default Home Screen when the phone is unlocked.

Search can now comb through app data, displaying information inline with other results, though developers have to rewrite their apps to take advantage of this feature. Search also does conversions such as distance and weight, solves math problems, provides shortcuts so you can communicate with contacts from the search results, displays stock prices when a company name or ticker symbol is searched, and looks up and displays live scores and weather forecasts.

Siri has learned a bunch of new tricks and sassy retorts, too. (Try asking her to divide zero by zero.) In iOS 9, Siri can be used to control lights and appliances, look up sports and movie data, read and write email and messages, answer questions, create reminders, and find information and directions about businesses. To find out more about what Siri can do, Apple's site has a list of the commands Siri recognizes.

The "Hey, Siri" functionality has been tweaked; previously, speaking aloud the phrase "Hey, Siri" when the iPhone was plugged in prompted Apple's virtual assistant to listen for your commands. In iOS 9, this feature is turned off by default; to enable it, you have to go through a quick training session in which the phone learns your voice.

Being proactive

iOS 9 now offers a lot more proactive results, with some system apps now trying to anticipate courses of action. If you receive an email that contains contact information or an invitation in the body of the message, Mail will suggest Calendar or Contact entries based on what it finds. Maps will display a notification in the lock screen when you enter your car and provide current traffic information to your destination (and will try to anticipate the destination based on your previous driving history).

And your last-played media app is brought to the forefront on the lock screen when the iPhone detects that headphones are plugged in or that the phone is connected to a Bluetooth device. And your schedule will be tracked, so if you consistently listen to podcasts on the drive to work but like to unwind with Pandora on the way back, the iPhone will learn and anticipate that behavior.

Calendar entries can be set to remind you when to leave for a destination based on current driving conditions. And when a call is received from a number that isn't in your contacts, the phone looks through previous emails and messages to find any numbers that may match. If so, it'll display a suggestion about who might be calling underneath the unfamiliar number.

Mind the apps

iOS 9 has a host of new and improved apps, with Maps being a standout. Its Transit app now offers detailed line and station information for buses, subways, ferries and trains in select cities (U.S. cities include Baltimore, Chicago, New York City, Philadelphia, San Francisco and Washington, D.C.).

The Search field in the Maps app has also been updated with pre-populated search categories (similar to the Search section that's to the left of the Home Screen). These categories show up over a text list of recent locations.

As noted, Maps tries to anticipate your destination and arrival time based on recent history when the phone detects you've entered a car. And during turn-by-turn navigation, Siri will now automatically volunteer details about what is causing a backup, even offering alternative routes if there are any.