So, barring any surprises – a Steve Jobs-esque “one more thing” – we have a pretty good idea of what to expect when Tim Cook heads out on stage on Wednesday. He’ll do it as the chief executive of the first US company to reach a value of $1tn (£768bn). To keep it that way, Apple will be building on past successes rather than introducing anything dramatically new.

We’ll likely see three new iPhones, a revamped Apple Watch, and maybe some new iPads. Later in the year, rumour suggests a budget laptop may be on the way.

What we won’t see, however, are some of the innovative leaps being promised by some of Apple’s competitors.

Samsung plans a device with a flexible display by the end of the year. OnePlus said its next phone will have a fingerprint sensor built into the screen. Huawei, which recently overtook Apple in global smartphone sales, has said it is working on a flexible device of its own.

But, of course, Apple’s strength is in ignoring such emerging technologies until they feel the time is right to build it into their products. As far as they see it, there’s no point in technology for technology’s sake – a philosophy that has been validated year after year.

"Right now the iPhone franchise is so strong that it feels like it's almost untouchable," says Ben Wood, an analyst at CCS Insight.

"Even at a time when rivals such as Samsung are having to push the envelope on developing new technology such as folding screens."

Last year, it was the iPhone’s 10-year anniversary, and fans were expecting a reinvention of the device. What they got was the iPhone X – Ten – that, while not revolutionising the range, did at least push it into something of a new design phase.

It also brought the iPhone into a new price bracket: $999.

Anticipation is not nearly as high this time around. This is what is referred to as an “S” year, when Apple doesn’t make any major changes to its device, save for some internal improvements – and tacks an “S” to the device name to make it clear.

So, in keeping with that theme, we’re expecting an iPhone XS. As well as that, leaks suggest another, larger version – one which may make $999 the “cheaper” option of the two. That bigger version might be called the XS Max, a name which to me sounds more like a muscle-building powder supplement, but hey - I’m not a marketer.

Apple’s stock price went up dramatically when the company revealed the average selling price of an iPhone was going up. Some had been concerned - Apple was very much testing the water with its iPhone X’s $999 price point last year, its most expensive phone ever. Twelve months on, the answer to “will people spend that much on an iPhone?” is, according to sales figures, an emphatic “yes”. With the XS Max we’ll see how far Apple can push it.

Beyond the XS and XS Max, completing the set in 2018 may be a budget version of the iPhone X. If so, that would mean the home button, the circular button that made the iPhone instantly recognisable, will be no more.

While the iPhone remains Apple’s bread and butter, accounting for the vast amount of the firm’s profits, a growing part of its business comes from other areas, such as the Apple Watch. The device hasn’t seen the blockbuster sales some might have expected since its launch in 2015 but it’s comfortably the biggest-selling smartwatch on the market.

Leaks suggest we may see a new Apple Watch with a slightly bigger screen and more sophisticated heart-monitoring capabilities. Three years since the original, I predict the Apple Watch being a big seller this Christmas – early adopters are primed to upgrade, and those who held back might now be tempted.

Apple Watch sales are good for Apple’s wider business – it only works with the iPhone, naturally.

How were the Apple leaks found?

Several rumour sites compete for tidbits of information about Apple's forthcoming products and often manage to share details before the tech giant would like them to be disclosed.

But at the end of last month, 9to5Mac's publication of what appeared to be official marketing images of one of the new iPhones and a new Apple Watch was a real coup for the site.

"To my memory, this is unprecedented," wrote the veteran Apple commentator John Gruber.

After much speculation about how he achieved his scoop, 9to5Mac's Guilherme Rambo has now revealed the technique he used via his Twitter account.

He wrote that he had studied the web addresses that Apple had used to host images of products announced at its last "special event" and deduced what the equivalents might be this time round.

He said he had not expected to find anything when he typed in the addresses, but was successful on his first attempt.

"Looking at the naming for past events, sometimes they combine multiple things into one recap image, which makes them harder to guess," he explained.

"We managed to guess the iPhone and Watch ones because they are 'hero' shots."

"Apple took them down immediately after we published," he added.

The iPhone-maker is likely to keep its secrets more closely guarded next time round.