A potential iPhone 5S or iPhone 6 release date has been leaked as June 20, with the claimed summer arrival coming just days after a potential WWDC 2013 unveiling. According to a leaked internal document from Japanese network KDDI, the service provider will reportedly start taking iPhone 5S pre-orders on June 20 ahead of an early July, a potential iPhone 5S release date that would suggest the iPhone 5 follow-on will be unveiled alongside the long awaited iOS 7 operating system at the manufacturer’s annual developer conference in June. With Apple CEO Tim Cook declaring in a recent earnings call that the company had a number of product ‘surprises’ in the works, recent iPhone 5S rumours have suggested the handset will be more of an incremental improvement ahead of a dramatic iPhone 6 overhaul.