It's been months since Apple rolled out iOS 8 to consumers, meaning the Cupertino-based company is likely at work on the next version of its mobile operating system, thought to be called iOS 9.

There's not much known about iOS 9 at this point, as Apple is notoriously secretive about what it's developing, though with its Worldwide Developers Conference coming up, we suspect more and more reports will begin to pop up, revealing clues as to what the software update might change or bring to the table.

Pocket-lint has therefore rounded up some of the earliest-known rumours and laid them out below, and we'll continually update this article as time goes by and things start to take shape. We've also included information about when and where Apple might first unveil iOS 9 to the world.

READ: Apple iOS 8 review

When will iOS 9 release?

Judging previous release patterns, Apple will likely roll out iOS 9 in autumn 2015, alongside the next generation iPhone or iPhones. The company released iOS 7 to consumers in September 2013, followed by iOS 8 in September 2014. It's therefore safe to assume iOS 9 will launch for iOS devices this September.

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READ: WWDC 2015: What to expect

Apple also tends to preview all major, new versions of iOS during its WWDC keynote, which is typically held annually in the summer. The purpose is not just to show consumers what's in the works, but also to educate developers and give them enough time to plan subsequent updates for their apps.

Apple recently announced it'll hold WWDC 2015 from 8 June to 12 June at Moscone West in San Francisco, where it'll likely make announcements that'll guide the conference's schedule for the remainder of the week.

What are the rumours saying?

iOS 9 is expected to be about fixes, optimisation, and stability rather than design tweaks and flashy features. The software is currently known by the codename "Monarch" at Apple.

Improvements

Apple reportedly plans to use iOS 9 as a software fix for several issues currently affecting iOS 8. Engineers are putting a huge focus on addressing bugs, maintaining stability, and boosting performance for the new operating system.

Many people criticised iOS 8 because it seemed to include an abnormal amount of bugs at launch, some of which caused issues like slow Wi-Fi, battery drain, Bluetooth connectivity failures, screen rotation problems, etc.

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READ: Apple pulls iOS 8.0.1 update that tried to fix HealthKit bug

Even Apple's smaller updates to iOS 8, such iOS 8.0.1, for instance, came with a whole new set of issues that disrupted cellular functions and disabled Touch ID on some devices, leaving consumers with broken devices.

If iOS 9 is indeed all about improvements, it wouldn't be the first time Apple took such a route: Snow Leopard notably brought stability optimisations to Mac OS X, where as Leopard from the previous year added all-new features.

Apple even marketed Snow Leopard with the tagline: "The world's most advanced operating system. Finely tuned."

Public beta

As part of an effort to curb future iOS mishaps, Apple allowed the public for the first time to test upcoming iOS updates. The company in March began allowing anyone to register and test iOS 8.3 before it rolled out to all consumers.

READ: Apple launches first iOS public beta

According to 9to5Mac, Apple plans to avoid another onslaught of major bugs and complaints by launching a public beta test for iOS 9 ahead of its release in September. We'll update this article when and if that happens.

Efficiency

iPhone and iPad owners should be happy to learn that Apple is also supposedly trying to reduce the amount of storage needed to install new updates and wants to make the iOS 9 update more efficient in terms of size.

In order to install iOS 8 on an iPhone or iPad, Apple said you needed 4.7GB or 6.9GB, respectively, of free storage space, forcing some customers, especially those who owned 16GB devices, to delete content and make room.

According to some reports, Apple noticed slow adoption rates for iOS 8 within the first months of its release, and many attributed that to the huge size of the software as well as the number of bugs it included.

All that might soon change however, as iOS 9 should weigh less and thus take up less of space.

Optimised for old devices

Most rumours have indicated the next major version of iOS will focus on performance and stability, rather than new and fancy features, but a more recent report has claimed iOS 9 will be different from past iOS releases because it'll have a second version optimised for aged devices like the iPhone 4S and iPad Mini.

 

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It's no secret that Apple's mobile operating system updates tend to work best on the latest phones and tablets, which is something that understandably annoys consumers who've already shelled out their hard-earned cash on pricey Apple gadgets, but 9to5Mac said Apple wants to change strategies with iOS 9.

It is supposedly building a "core version" of iOS 9 that's just for A5-powered iOS devices. The company would previously build just one new version and then remove features for old devices that didn't perform well during testing, though that approach often resulted in bugs and a sluggish performance.

This seperate version of iOS 9 will instead enable each properly-performing feature one-by-one, according to 9to5Mac, which should breathe new life into an entire generation or two of older iPhones, iPads, and even iPod touches. 

READ: Here's how to get ready for and install iOS 8

Will iOS 9 have any new features?

It looks like Apple simply wants to perfect iOS with under-the-hood improvements and worry later about adding new tricks for eager customers. That said, we're assuming iOS 9 will include some new features, as it might be hard for the company to market a major update that doesn't have any fancy additions.

Apple implemented a major design overhaul with iOS 7, and the following year with iOS 8, it added features like Continuity, Apple Pay, and support for extensions and widgets. It's possible Apple might fine tune those features in iOS 9, but again, it should also introduce something new.

Proactive

Apple plans to unveil a deep search feature with iOS 9. It is codenamed Proactive and has been in development for several years, it's claimed.

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According to 9to5Mac, Proactive is capable of leveraging data from Siri, Contacts, Calendar, Passbook, and third-party apps to automatically provide timely and relevant information based on your history and device-usage patterns. Proactive therefore sounds like it'll be Apple's take on Google's Google Now assistant.

When Proactive fully launches, it will most likely live on the left of the Home Screen, where Spotlight could be accessed prior to the iOS 7 redesign. It will also have a dedicated Search Bar for you to access exisiting features of Spotlight (including the ability to search for names or launch apps, etc). But Proactive will be different in that it will display news stories as search results.

Proactive's interface will also live below the search bar and focus on displaying content from and related to Apps, Contacts, Maps, and an upgraded version of Siri. It will push notifications and integrate with core iOS apps as well, including Apple’s Maps, allowing it to display custom points of interest using a new augmented reality interface, among many other things.

It's not yet definite if Proactive will launch with iOS 9 or continue to slowly roll out in bits and pieces, but we should hear more about the feature at WWDC 2015 in June.

READ: Apple is working on a Google Now-like feature to replace Spotlight in iOS 9

HomeKit and Home app

Apple developed the HomeKit framework so it could simplify the current state of home automation. It's essentially a common language that smart devices from any manufacturer can understand and support. HomeKit also leverages Siri, Apple's voice assistance, letting you control smart devices with just your voice.

HomeKit technically debuted with iOS 8 last autumn, though it has yet to be activated or "launched" by Apple. Also, for a long time there was no evidence to indicate a HomeKit app. HomeKit was thought to run in the background of iOS 8, controlling your smart devices either directly or indirectly via Siri and Geolocation.

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Thats said, according to 9to5Mac, Apple plans to let you manage HomeKit devices through a new iOS 9 app called Home. So, using either Siri through Apple TV or the Home app, you should be able to remotely control your home from iOS devices. The Home app is expected to debut with iOS 9 at WWDC.

The app is basic in functionality: it can wirelessly discover and set up HomeKit devices and create a virtual representation of your home. Doing so will allow you to easily organise and connect HomeKit devices. It can also use the Apple TV as a hub for connecting all HomeKit devices and even offers help tips for finding HomeKit devices and apps.

HomeKit will also rely upon the Home app to securely manage a smart home full of accessories and data.

READ: Apple HomeKit explained

Transit directions

Apple's Maps app in iOS 9 will supposedly add transit directions for subway, train, and bus lines, according to 9to5Mac. The app currently doesn't offer public transit directions, leaving you with no option but to use third-party apps like Google Maps. The new transit feature is expected to be the major addition to Maps.

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The app will not only offer routing options, but also a trip planner and Transit map view that'll join Standard, Hybrid, and Satellite. Apple has also spent time refining data, adding new cities, and developing a new push notifications system that will notify users as new cities gain support for transit navigation.

Apple is also working toward indoor mapping, but that won't be ready for iOS 9, it's claimed.

iPad multi-tasking

Apple wants to release a 12-inch iPad called iPad Pro later this year, 9to5Mac has reported. But, in the mean time, it is it'll unveil some iPad software changes at WWDC. Apple will show off a split-screen mode that'll let users run multiple apps side-by-side.

Apps will be able to take up a third, half, or two-thirds of the display - or one app might be able to be open twice and run side-by-side.

Redesigned Siri

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9to5Mac also revealed a few details about Siri in iOS 9. The next major version of the iPhone and iPad operating system is said to have a redesigned Siri interface that mirrors the colourful design of Siri on Apple Watch, though not much else is known about the redesign at this time.

READ: iOS 9 might not have any new features

Want to know more?

Other rumours have indicated Apple has plans to use the new San Francisco font that was introduced with the Apple Watch. It'll replace the Helvetica Neue font used in iOS 7/iOS 8 and OS X Yosemite.

Our iOS 9 hub has all the latest news about Apple's next major update to iOS.