Interestingly, it wasn’t called iOS at that time – it was just iPhoneOS till iOS 3, or it was called then – iPhone OS 3. Thus ... the battery cell icon automatically turns red – but ...

A year later, it received this boring sobriquet: iPhone OS 1. By 2010, marketing got its act together and came up with "iOS," just in time for the debut of version 4. We're now up to iOS 18 .