Los Angeles-based Burstly, the developer of app analytics and testing software, has quietly been acquired by Apple. Financial terms of the buy were not disclosed. The acquisition is not a surprise to Apple app developers, who have widely adopted the company's tools. The company has said that over half the apps in the Apple App store use its tools. Burstly was venture backed by GRP Partners, Rincon Venture Partners, SoftBank Capital, and Founder Collective, and was led by Evan Rifkin. Burstly acquired TestFlight back in 2012. Rifkin is a serial entrepreneurs, having succesfully sold his prior firm--TagWorld/Social Project--to MTV.