报错:An instance 0x102c1aa00 of cl

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");

}