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/.
Last year's 4.7-inch-screened model is the most adopted iPhone of all the ones on the market, says mobile marketing and analytics firm Localytics, while the 5.5-inch version didn't fare as well. One year after its release, the iPhone 6 is the most popular iPhone model around. Apple's iPhone 6 is the most popular iPhone out there, according to a new report. The iPhone 6 holds a leading 30 percent share among all iPhones on the market, mobile marketing and analytics firm Localytics said on Tuesday.