addSubview时EXC_BAD_ACCESS代码1

Question

模拟器中不会发生此错误，但会在手机上发生。我有5个不同的webViews，我有一个菜单设置，以便当选择一个菜单时，它将被添加为子视图，其他webViews将从superview中删除。

// MARK: - Hides all other webviews and shows selected
func hideOtherWebViews(selectedWebView: WKWebView!){
    self.navBarFixed = false
    dispatch_async(dispatch_get_main_queue(), { () -> Void in
        if checkLoaded.currentWebView != self.selectedWeb{
            for webview in [self.facebookWeb, self.instagramWeb, self.googleplusWeb, self.twitterWeb, self.youtubeWeb, self.linkedinWeb]{
                // If it isn't the selected web view do this
                if webview != selectedWebView{
                            webview.removeFromSuperview()
                            println("web hidden")
                    // If it is the selected web view do this
                }else{
                    self.centerView.addSubview(webview)
                    webview.setTranslatesAutoresizingMaskIntoConstraints(false)

                    //webview constraints
                    let top = NSLayoutConstraint(item: webview, attribute: .Top, relatedBy: .Equal, toItem: webview.superview, attribute: .Top, multiplier: 1, constant: 0)
                    let right = NSLayoutConstraint(item: webview, attribute: .Right, relatedBy: .Equal, toItem: webview.superview, attribute: .Right, multiplier: 1, constant: 0)
                    let left = NSLayoutConstraint(item: webview, attribute: .Left, relatedBy: .Equal, toItem: webview.superview, attribute: .Left, multiplier: 1, constant: 0)
                    let bottom = NSLayoutConstraint(item: webview, attribute: .Bottom, relatedBy: .Equal, toItem: webview.superview, attribute: .Bottom, multiplier: 1, constant: 0)

                    self.view.addConstraints([ top, right, left, bottom])

                    webview.scrollView.delegate = self
                    webview.navigationDelegate = self
                    webview.UIDelegate = self
                    webview.scrollView.showsHorizontalScrollIndicator = false
                    webview.scrollView.showsVerticalScrollIndicator = false
                    self.whiteOverlay.alpha = 1
                    UIView.animateWithDuration(0.2, animations: { () -> Void in
                        self.whiteOverlay.alpha = 0
                    })
                }
            }
        }

    })

错误发生在

上

self.centerView.addSubview(webview)