WatchOS 4

WatchOS 4 is the fourth major release of watchOS for the Apple Watch that was designed, developed and distributed by Apple Inc. It was announced at WWDC 2017 alongside iOS 11, tvOS 11 and macOS High Sierra preceding a developer beta and released on September 19th to the general public of the same year. WatchOS 4 was the predecessor to watchOS 5 and the successor to watchOS 3.