1.错误描述：
An instance 0x11642da00 of class WKWebView was deallocated while key value observers were still registered with it. Current observation info: <NSKeyValueObservationInfo 0x1708316e0> ( <NSKeyValueObservance 0x170648b50: Observer: 0x117910cc0, Key path: title, Options: <New: YES, Old: NO, Prior: NO> Context: 0x0, Property: 0x170643c90>
2.原因：因为没有移除WKWebView的监听方法
//添加获取web页面title的监听
[self.webView addObserver:self forKeyPath:@"title" options:NSKeyValueObservingOptionNew context:NULL];
3.移除KVO监听方法
-(void)dealloc{
[self.webView removeObserver:self forKeyPath:@"title"];
NSLog(@"WebViewController-dealloc");
}
