According to this reddit thread[1] they were sued for patent infringement[2] [1]...

		_oghd on Dec 3, 2015 \| parent \| context \| favorite \| on: Swift is Open Source According to this reddit thread[1] they were sued for patent infringement[2] [1] https://www.reddit.com/r/apple/comments/1xuzif/what_ever_hap... [2] http://www.bbc.com/news/technology-20236114