The new version comes just two weeks after the release of iOS 7.1's third developer preview, and is now available to download from Apple's developer website and over-the-air on test devices. People familiar with the update told AppleInsider that beta 4 sports build number 11D5134c, and ships alongside Xcode 5.1 build number 5B90f.
A bug that previously caused messages to show a failure message immediately after sending is believed to have been fixed. The Bluetooth stack is said to remain an area of concern, however, as 32-bit apps reportedly still do not function properly on 64-bit devices such as Apple's all-new iPad Air and flagship iPhone 5s.
Xcode, for its part, is said to have received a significant number of updates in its latest beta incarnation. Interface Builder has reportedly seen a number of tweaks and performance improvements, notably a decrease in CPU and system memory utilization when drawing storyboards on Mac OS X 10.8.
Applications being built for the Mac App Store which require a provisioning profile reportedly may not build correctly or may crash at launch with a "Permission Denied" error in the latest beta, requiring developers to manually select a different build setting. In addition, it is said that developers attempting to simulate iOS versions earlier than iOS 6.1 in Mavericks may experience performance issues and could stop responding to the computer's hardware keyboard.
Apple is believed to be preparing iOS 7.1 for a March release.