WKWebView added as Subview is not resized on rotation in Swift
I managed to solve the problem by using this line of code:
self._webView!.autoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight:)
swift 3 version:
webView?.autoresizingMask = [.flexibleWidth, .flexibleHeight]
I'm posting an answer for Objective-C, just in case if someone comes here looking for it
[self.webView setAutoresizingMask:UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth];