Predicting what Apple will unveil at its yearly Worldwide Developers Conference (June 13-17) is as exact a science as timing an earthquake. Or choosing the winning Toto numbers. Take your pick.

Will it be the latest iPhone? A brand new MacBook? The long-rumoured Apple car? The last two conference keynotes included no hardware announcements at all.

But since 2012, Apple has used the keynote event of every WWDC to introduce new iterations of its iOS and OS X operating systems. At this conference, developers from all over gather to find out about upcoming software and hardware developments in the Apple ecosystem.

Apple watchers, as always, are reduced to speculating what this famously secretive company will pull out of its hat.

Might the switch from the usual venue, Moscone West Convention Center, to the larger Bill Graham Civic Auditorium indicate something different from usual? Perhaps there might be new hardware after all? This auditorium, after all, was where Apple chose to launch the iPhone 6s and 6s Plus last September.

Apart from the keynote (June 14, 1AM SGT) and some first-day sessions, all the WWDC seminars and workshops will still take place at the usual Moscone West. But the larger capacity venue for the keynote might mean that more media are expected, which might in turn mean more announcements.

So, here are several educated guesses based on past WWDCs and what we gather around the Internet.

iOS 10

There will definitely be a new iOS. But what will be its main features?

The rumour mill suggests that Apple will finally introduce a Siri SDK that allows Siri to be used with third-party apps.

There will be more 3D Touch options, such as sharing photos from the 3D Touch panel and easier access to app functions. The Music app is said to be re-designed for a more intuitive user-interface. The entire iOS might get a dark theme, similar to the current OS X El Capitan's option for dark menu bar and dock.

The much-maligned Maps app will be upgraded to make it more accurate and expand public transit coverage in more cities.

Since the coming iPhone 7 Plus is rumoured to have a dual-lens camera, the Camera app will probably gain some new features, such as depth-of-field preview. But revealing them at WWDC might give away too much about the new iPhone.

OS X 10.12 (or MacOS)

Will Apple standardise naming conventions across the board - you know, iOS, tvOS, watchOS… If so, perhaps OS X will be renamed MacOS 10.12 or MacOS 11.

Or perhaps Apple will choose yet another California landmark? MacOS Warriors would be a great idea. Especially if the Golden State Warriors win a second NBA championships in a row.

Anyway, the new MacOS is said to gain Siri functionality, just like Cortana in Windows 10. You should also be able to unlock your Mac using your iPhone or Apple Watch, as part of the expanded Continuity features.

If the Music app gets a design overhaul, we will see the same for iTunes.

The Photos app is also rumoured to gain features lost when it moved from iPhotos. We hope to see more brushes for adjusting brightness and contrast as well as more options for the photo books.

tvOS and watchOS

With new iOS and macOS, we will definitely see new tvOS and watchOS 3.

Details about these two operating systems are pretty scarce. But we do know that Apple requires all Apple Watch apps to be native apps as of June 1. Native apps allow better performance, such as quicker starting.

App Store

In a rare pre-WWDC interview with The Verge, a US tech site, Apple's marketing chief Phil Schiller revealed that Apple will be opening up app subscriptions to include all product categories instead of the current limited genres such as audio or video streaming, and news publications.

Apple will also be introducing a new subscription revenue split. Currently, Apple takes 30 per cent of the subscription fees customers pay. But from the second year, Apple's share will be halved, such that the app developers and merchants (for example, Spotify and Netflix) will earn 85 per cent instead of 70 per cent.

All current subscriptions are eligible - if developers have subscribers they have already retained for over a year, the revenue split will start immediately on Monday, June 13.

To get developers even more excited, Apple is finally introducing Search Ads. It will appear as the first listing in search results on the App Store for iPhone and iPad and will be clearly marked as such. Furthermore, the developer only pays when a user taps on the ad. Users will not be tracked and their data will not be shared with any developers.

We are sure Mr Schiller will reveal more updates about the App Store during the WWDC keynote.

Hardware

It is strange with all the Apple iMac having 4K and 5K Retina displays, there are still no Thunderbolt 4K or 5K monitors from Apple. A recent leak shows limited stock of Apple's current Thunderbolt monitors. So, we might finally see a 4K or 5K Thunderbolt Display.

Some rumours also pointed to new MacBook Pros, with an OLED bar above the keyboard, being introduced. But we are not too optimistic on that front.

The Straits Times will be in San Francisco to bring you the latest announcements from Apple.