With the Apple iOS 4 scheduled for release to public on June 21 – three days before the new iPhone 3 hits markets June 24 -, the company has begun soliciting apps for the forthcoming OS, urging the developers to submit their apps at the earliest. A developer preview of iOS4, earlier called iPhone OS 4, was launched in early April.

Advising the developers to ensure that their apps have been built and tested “using iOS 4 and iPhone SDK 4 GM seed available from the iPhone Dev Center,” developers’ site of Apple specified: “Log in to iTunes Connect and submit your iOS 4 application now, so it will be ready for sale when iOS 4 is available to iPhone and iPod touch users.”

According to the information forwarded by the Apple executives, more than 100 new user features have been added to the new OS, which now boasts some of the fervently-requested enhancements, including “tentpole” improvements like multitasking, background location, and background task completion.

While the iOS 4 is forthcoming, Apple has also recently released an iTunes Connect Mobile app, featuring a suite of Web-based tools to help developers in submitting and managing their apps; as well as accessing their sales and trend data.

The ‘free’ iTunes Connect Mobile app is compatible with iPhones, iPod touches, and iPads running iPhone OS 3.0 or later.