Yet keeping Apple's business is no sure thing. Companies in one version of an iPhone or iPad can just as easily face an existential moment if dropped from the next - a lesson learned by suppliers such as Audience Inc. and TPK Holding Co.
"With Apple, the business is won and lost in huge chunks," Audience CEO Peter Santos said in an interview earlier this year. The maker of audio components saw its revenue from Apple plummet to less than 1 per cent this year from 82 per cent of total sales in 2010 after it was left out of the iPhone 5. "You're in a model or you're not," he said.
Apple will unveil the latest iPhones and a wearable gadget near its headquarters in Cupertino, California. The iPhones will have 4.7-inch and 5.5-inch screens and will include software that lets the handset act as a mobile wallet, while the watch-like wearable device is expected to include features for tracking health and fitness activity, people familiar with the plans have said.
Chris Gaither, a spokesman for Apple, said the company doesn't comment on suppliers. Representatives from TSMC, Samsung, GT Advanced, TPK and NXP also declined to comment.
The debut of new products will showcase the influence of landing Apple's business. At least nine publicly traded companies get more than 40 per cent of their revenue from Apple, according to a supply-chain analysis compiled by Bloomberg.
Dialog Semiconductor, which makes power-management chips for the iPhone, has the most exposure, with 80 per cent of its $903 million in revenue last year tied to Apple, according to the data.
While Dialog CEO Jalal Bagherli declined to say whether Apple is a customer, he said big companies like Apple are "the customer everyone is after. And if you're in four or five of their products, it's like you're already getting diversification."
Dialog, based in Reading, Britain, works with its biggest customer as if it's an "extension of the R&D team," Bagherli said, without mentioning Apple by name. "You have to be willing to change daily as they figure out what their product will be. Most companies don't want to do that, because it can be quite painful. But we jump through all the hoops we need to jump through."
By collaborating so closely on product design, it's harder for a competitor to replace Dialog, Bagherli said. That strategy has worked, with the company's sales more than quintupling since 2008.
Still, Apple has a reputation as a tough negotiator with suppliers and has shown little loyalty if it can get a better price or more advanced technology elsewhere, said Francis Sideco, a senior manager at IHS Inc., which studies components used in the iPhone.
"They aren't in it for charity," Sideco said. "Apple typically hasn't shown any undue loyalty to any one supplier, and just because you're the guy that's there, they aren't going to stick with you because you're the incumbent."
Apple's employees burrow into the operations of its suppliers, studying costs for labor and materials to determine the price it will pay for components, two former Apple engineers said. Apple leaves companies little room to negotiate, especially for those that have hitched themselves to the iPhone, which sold 150 million units last year, said the ex-employees, who asked not to be identified because they're not authorized to disclose Apple's process.
"If Apple decides not to do it, they need to find new customers," said Dick James, senior technology analyst at Chipworks, which studies the components inside consumer electronics devices.
Companies such as Audience and touch-screen designer TPK know firsthand the consequences of relying too much on Apple and serve as cautionary tales for others now banking on the iPhone. Both companies saw orders from Apple curtailed when new iPhone models were introduced, and their balance sheets and stock prices were bruised as a result.
Taipei-based TPK was an early beneficiary of the iPhone, providing screens that gave the device groundbreaking touch controls. Largely on the strength of its Apple ties, the company held an IPO in 2010.
In 2012, Apple changed the design of its iPhone screens and began using TPK rivals such as LG Display Co. instead, according to a former TPK executive. TPK's entire business was undercut. To keep any Apple business, it had to become a supplier that laminates together screens made by other companies, a lower-cost task with thinner profit margins, said the person, who asked not to be identified because of nondisclosure agreements.
TPK, which still gets about 41 per cent of its revenue from Apple, remains a supplier for the iPad, another person familiar with the relationship said.
Investors have punished TPK for its lower standing with Apple, sending the supplier's stock down 73 per cent since an all-time high. TPK's net income last year fell about 50 per cent.
Similarly, Audience told investors that it might not be in the iPhone 5 shortly before the device came out in 2012, sending its stock down to $6.90 from $18.86. Apple wasn't telling Audience one way or another, so to confirm its suspicions, the company's engineers bought a new iPhone when it came out and did their own tear-down analysis, Santos said.
While Audience, based in Mountain View, California, has replaced much of the lost revenue through sales to Samsung, which is now the source of 72 per cent of its revenue, the component maker's stock price is far below its Apple-era highs.
"Getting through this was harder than doing the IPO," Santos said.
That isn't keeping executives from making trips to Cupertino to show Apple their latest technology. According to Barclays Plc, other companies supplying components in the next iPhone include chipmakers Avago Technologies Ltd. and Skyworks Solutions Inc. A gyroscope made by Sunnyvale, California-based InvenSense Inc. also may be added to the phone instead of those from rivals STMicroelectronics NV and Bosch Sensortec GmbH, Barclays said. The companies declined to comment.
Some companies are trying to diminish a dependence on Apple. Dialog has recently increased efforts to move into new markets. Cirrus Logic Inc., a maker of audio components that gets 73 per cent of its revenue from Apple, purchased rival Wolfson Microelectronics, which has been adding non-Apple customers after getting dropped from the iPhone. Even Foxconn Technology Group, the company that assembles Apple's products in China, has been making an effort to diversify its business.
"One minute you're in a product," Derek Milne, a spokesman for Wolfson, said this year. "And one minute you can be out."