Apple's iPhone 6 and its big brother the iPhone 6+ are the best-selling iPhone models of all time, with the iPhone 6 coming out ahead by approximately one-third. These iPhone models have broken sales records since their introduction in early November 2014, giving competitors another reason to work harder for smartphone supremacy.

Barely three months after its release, the iPhone 6 generated 71.5 million unit sales, far outpacing its predecessor, the iPhone 5S, by 30%. The larger iPhone 6+ now accounts for 40% of all tablet-style smartphone sales and is the second-best selling iPhone of all time. Although the Cupertino, CA-based company tends not to break down iPhone sales figures by particular models, it's estimated that as of June 2017, roughly 222.4 units of this generation have been sold. That compares with around 78.3 million units of its successor, the iPhone 7 and 7+, to date.

Released in 2013, the iPhone 5 accounted for 70 million unit sales, and the iPhone 5S recorded 52 million unit sales. These were Apple's top sellers until the 2014 release of the faster iPhone 6 and the larger Phone 6+. Revenue estimates for the iPhone 6 are set between $65.2 and $68 billion dollars, surpassing iPhone 5 revenues of $45.6 billion.

By mid-2019, iPhone sales had dropped off considerably from the peak achieved with the iPhone 6 and 6+, and the industry was hotly anticipating a new crop of smartphones with 5G capabilities in 2020, which promised groundbreaking features. AS part of the anticipation, abruptly canceled a planned upgrade.

Part of the rumor pointed to a return to a smaller form factor in its premium phone offering, which was thought to be a smart move for Apple, which had recorded excellent sales with its smaller models, particularly the iPhone SE.