WKWebView bottom constraint set but won't work

I have set WKWebView bottom constraint to superview but it won't display till superview instead displays content till safe area.

Here is the problem image that displays the bottom part doesn't fill properly.

And here is the hierarchy of view and constraints image

And code to setup WebView constraints with container view

    let wv = WKWebView(frame: containerView.frame, configuration: wvConfig)
    webView = wv
    containerView.addSubview(wv)

    // setup constraints
    wv.translatesAutoresizingMaskIntoConstraints = false
    if #available(iOS 11.0, *) {
        wv.trailingAnchor.constraint(equalTo: containerView.trailingAnchor).isActive = true
        wv.leadingAnchor.constraint(equalTo: containerView.leadingAnchor).isActive = true
        wv.topAnchor.constraint(equalTo: containerView.topAnchor).isActive = true
        wv.bottomAnchor.constraint(equalTo: containerView.bottomAnchor).isActive = true
    } else {
        NSLayoutConstraint(item: wv, attribute: .top, relatedBy: .equal, toItem: containerView, attribute: .top, multiplier: 1.0, constant: 0).isActive = true
        NSLayoutConstraint(item: wv, attribute: .leading, relatedBy: .equal, toItem: containerView, attribute: .leading, multiplier: 1.0, constant: 0).isActive = true
        NSLayoutConstraint(item: wv, attribute: .trailing, relatedBy: .equal, toItem: containerView, attribute: .trailing, multiplier: 1.0, constant: 0).isActive = true
        NSLayoutConstraint(item: wv, attribute: .bottom, relatedBy: .equal, toItem: containerView, attribute: .bottom, multiplier: 1.0, constant: 0).isActive = true
    } 

So, Can anyone rectify issue here?

from WKWebView bottom constraint set but won't work