iPhone 6 will be released on September 12
The iOS 8 version is expected to be released 100 days after its debut at WWDC. That's why Apple can launch iOS 8 on September 10 (Wednesday) and iPhone 6 on September 12 (Friday).
A big change in design
Specifically, iOS 6 was introduced on June 11 and released on the following 100th day ( Wednesday, September 19 ) and then two days later, on Friday, iPhone 5 was released. Similarly, iOS 7 debuted on the 10th, released 100 days later, exactly on Wednesday 18 September, and then 2 days later, on Friday 20th September, iPhone 5S and 5C were released.
iPhone 6
Apple iPhone products have recently launched on Friday, 2 days after the operating system officially launched. That's why you can expect that September 12 is the day the iPhone 6 comes out.