Rumor: Fourth beta of Apple's iOS 8 expected to arrive Monday, July 21

The alleged release date for developers was revealed on Wednesday by BGR, citing an Apple source. The date is consistent with Apple's typical two-week gap in between new releases, though the same publication was off by one day in its predicted iOS 8 beta 3 release date.

If Apple continues its pattern, it's likely that the next beta of OS X Yosemite will also arrive next week. Both free software updates are scheduled to launch this fall.

iOS 8 beta 3 introduced Wi-Fi calling for iPhones running on the T-Mobile network in the U.S. Canadian carrier Rogers Wireless also plans to support the iOS 8 Wi-Fi calling feature.

The last beta of iOS 8 also came alongside a slew of beta software releases, including Xcode 6, Find My iPhone 4.0, Find My Friends 4.0, and Apple Configurator 1.7.

The second beta of iOS 8, released last month, made Apple's Podcasts application a native, built-in app for iPhone users. It also marked the iPad debut of the new QuickType keyboard, which suggests words as users type.

Scheduled to launch this fall, iOS 8 features support for third-party keyboards and Siri-based controls of smart home appliances. It will also include a new Health application that will collect users' health and fitness data, while the Touch ID fingerprint sensor on the iPhone 5s will become accessible for third-party developers to tap into.