分段故障：11、xcode -12

Question

該應用程序正在 xcode 11 上運行，但是一旦我在 xcode 12 上運行它，它就會給出分段錯誤：11 錯誤。

表單調試發現問題出在這個 function 中，如果我注釋代碼它工作正常，對我來說似乎沒有任何錯誤，有什么發生嗎？

open func addViewController(_ vc:UIViewController)->Void{
    
    controllers.append(vc)
    
    // Setup the viewController view
    
    vc.view.translatesAutoresizingMaskIntoConstraints = false
    scrollview.addSubview(vc.view)
    
    // Constraints
    
    let metricDict = ["w":vc.view.bounds.size.width,"h":vc.view.bounds.size.height]
    
    // - Generic cnst
    
    vc.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[view(h)]", options:[], metrics: metricDict, views: ["view":vc.view] as [String: UIView]))
    vc.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[view(w)]", options:[], metrics: metricDict, views: ["view":vc.view] as [String: UIView]))
    scrollview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-0-[view]|", options:[], metrics: nil, views: ["view":vc.view] as [String: UIView]))
    
    // cnst for position: 1st element
    
    if controllers.count == 1{
        scrollview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-0-[view]", options:[], metrics: nil, views: ["view":vc.view] as [String: UIView]))
        // cnst for position: other elements
    } else {
        
        let previousVC = controllers[controllers.count-2]
        if let previousView = previousVC.view {
            // For this constraint to work, previousView can not be optional
            scrollview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[previousView]-0-[view]", options:[], metrics: nil, views: ["previousView":previousView,"view":vc.view] as [String: UIView]))
        }
        
        if let cst = lastViewConstraint {
            scrollview.removeConstraints(cst)
        }
        lastViewConstraint = NSLayoutConstraint.constraints(withVisualFormat: "H:[view]-0-|", options:[], metrics: nil, views: ["view":vc.view] as [String: UIView])
        scrollview.addConstraints(lastViewConstraint!)
    }
}

Answer 1

像這樣的部分代碼

let metricDict = ["w":vc.view.bounds.size.width,"h":vc.view.bounds.size.height]

,

["view":vc.view] as [String: UIView]

和

["previousView":previousView,"view":vc.view] as [String: UIView]

可能會導致該問題，因此您可以嘗試輕量級分段工作，以便編譯器可以從中傳遞

open func addViewController(_ vc:UIViewController)->Void{
    
    controllers.append(vc)
    
    // Setup the viewController view
    
    vc.view.translatesAutoresizingMaskIntoConstraints = false
    scrollview.addSubview(vc.view)
    
    // Constraints
    
    let metricDict:[String:CGFloat] = ["w":vc.view.bounds.size.width,"h":vc.view.bounds.size.height]
    
    // - Generic cnst
    
    let con:[String: UIView] = ["view":vc.view]
    
    vc.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[view(h)]", options:[], metrics: metricDict, views: con ))
    vc.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[view(w)]", options:[], metrics: metricDict, views: con ))
    scrollview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-0-[view]|", options:[], metrics: nil, views: con ))
    
    // cnst for position: 1st element
    
    if controllers.count == 1{
        scrollview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-0-[view]", options:[], metrics: nil, views: con))
        // cnst for position: other elements
    } else {
        
        let previousVC = controllers[controllers.count-2]
        let relt:[String: UIView] = ["previousView":previousView,"view":vc.view]
        if let previousView = previousVC.view {
            // For this constraint to work, previousView can not be optional
            scrollview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[previousView]-0-[view]", options:[], metrics: nil, views:relt ))
        }
        
        if let cst = lastViewConstraint {
            scrollview.removeConstraints(cst)
        }
        lastViewConstraint = NSLayoutConstraint.constraints(withVisualFormat: "H:[view]-0-|", options:[], metrics: nil, views: con)
        scrollview.addConstraints(lastViewConstraint!)
    }
}