Apple's iOS 12.4 testing rolls on  today.

iOS 12.4 beta 4 is now available to developers, who can get the update by going into Settings > General > Software Update on their iPhone or iPad. The update is also available through Apple's Developer Center on the web.

A public beta version of iOS 12.4 beta 4 for people in the Apple Beta Software Program should be available shortly.

There haven't been any major new features found in the iOS 12.4 beta releases so far. Apple has said that it will launch its Apple Card in the U.S. this summer, so it's possible that iOS 12.4 will support Apple Card when it's released to the public. Other than that, though, iOS 12.4 may be focused on performance improvements and bug fixes.

Apple also released watchOS 5.3 beta 3 to developers today. No major new features have been found in the update thus far.