Apple Inc. (NASDAQ:AAPL) is gearing up to release its big screen iPhone 6 on September 9, along with a slew of new products and services. It has developers stressed out. They are doing everything possible to ensure that their apps will work on the iOS 8. The new operating systems, which was announced at WWDC in June, will expand Apple’s ecosystem beyond the smartphones and tablets.

Apple iPhone 6
iPhone 6 Mockup Image

Apple’s biggest software update since the App Store

It represents huge opportunity for the Cupertino-based company’s more than nine million registered app developers, says Cadie Thomson of CNBC. But it’s also “a big headache” for developers because they have to build apps for as-yet unknown products and meet consumers’ high expectations, said Matt Johnston, chief technology officer at app testing firm Applause.

Apple CEO Tim Cook said at the WWDC event that it is the biggest software update from Apple since the company launched App Store in 2008. The iPhone maker’s App Store generated $10 billion in revenue last year. With two new models of the iPhone and a new iWatch, the monetization opportunity will be even bigger. The tech giant introduced app extensions with the iOS 8, essentially to get developers to start building apps for devices beyond the iPhone. The company is pushing into the “Internet of Things.”

Apple offers several tools to help developers

Johnston said app testing is going to get a lot more complex as there are a new set of challenges. Two new iPhones with different screen sizes will add to developers’ problems, said Y-Media Labs chief executive Ashish Toshniwal. They will have to design their apps for each device. Though the iPhone maker offers tools in iOS 8 that help developers make apps for multiple form factors, that’s not a perfect solution. These things could work well in lab testing, but often fall apart in the users’ hands.

Despite all the challenges, developers have to make sure their apps work properly from day one of the launch. Consumers expect perfection. They have come to believe that things are just going to work. As the development and testing have become more complex, apps risk falling down on users’ expectations, at least in the beginning.

To avoid a day one mishap, they have started preparing for the iOS 8 roll out much earlier than they have for the past iOS launches.