The equals sign means is equal to. It is telling us that one thing equates to another; that they are the same.
The iPhone 4 is the most recent iPhone to be discontinued from the iOS Update cycle. It did not receive the iOS 8 update, so it's final software version is iOS 7.1.2. You can update to this version through iTunes, or download it from an IPSW repository like this website: https://ipsw.me/.
Apple has an extremely busy 12 month period ahead, with two potential iPhone devices earmarked for release. It is increasingly expected that Apple will release an upgraded version of the iPhone 6 in 2015, and may name this the iPhone 6s, with a revolutionary iPhone 7 to follow during 2016.t is increasingly expected that Apple will release an upgraded version of the iPhone 6 in 2015, and may name this the iPhone 6s, with a revolutionary iPhone 7 to follow during 2016.