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iOS Introduction to Auto Layout in iOS Visual Format Language Blues and Purples Again!

Dmitri LaCour
PLUS
Dmitri LaCour
Courses Plus Student 10,545 Points
Posted by Dmitri LaCour
Dmitri LaCour
Courses Plus Student 10,545 Points

VFL throwing "unrecognized selector sent to instance" error in Xcode 9.2

I am working with Xcode 9.2 on the Visual Format Language portion of Introduction to Auto Layout in iOS course and am having issues setting up my purple and blue views. The code is below and the areas causing an issue are the second and third view.addConstraints. I've looked for typos and compared it against the code in the video but can't seem to fix it. What am I missing?

Also, Xcode forced me to add as AnyObject to my metrics dictionary. Can anyone explain why?

orangeView.backgroundColor = UIColor(displayP3Red: 255/255, green: 148/255, blue: 0, alpha: 1)
purpleView.backgroundColor = UIColor(displayP3Red: 187/255, green: 44/255, blue: 162/255, alpha: 1)
blueView.backgroundColor = UIColor(displayP3Red: 122/255, green: 206/255, blue: 255/255, alpha: 1)

orangeView.translatesAutoresizingMaskIntoConstraints = false
purpleView.translatesAutoresizingMaskIntoConstraints = false
blueView.translatesAutoresizingMaskIntoConstraints = false

view.addSubview(orangeView)
view.addSubview(purpleView)
view.addSubview(blueView)

let views: [String: AnyObject] = [
            "orangeView": orangeView,
            "purpleView": purpleView,
            "blueView": blueView,
            "topMarginsGuide": view.layoutMarginsGuide.topAnchor
        ]

        let metrics: [String: AnyObject] = [
            "orangeViewWidth": 200 as AnyObject,
            "orangeViewHeight": 57 as AnyObject,
            "standardOffset": 8 as AnyObject,
            "bottomSpaceOffset": 50 as AnyObject
        ]

        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[orangeView(orangeViewWidth)]", options: [], metrics: metrics, views: views))
        orangeView.centerXAnchor.constraint(equalTo: view.centerXAnchor)
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[topMarginsGuide]-standardOffset-[purpleView]-standardOffset-[orangeView(orangeViewHeight)]-bottomSpaceOffset-|", options: [], metrics: metrics, views: views))
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[topMarginsGuide]-standardOffset-[blueView]-standardOffset-[orangeView]", options: [], metrics: metrics, views: views))
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-standardOffset-[purpleView(==blueView)]-standardOffset-[blueView]-standardOffset-|", options: [], metrics: metrics, views: views))

1 Answer

micram1001
micram1001
33,833 Points
micram1001
micram1001
33,833 Points

You need to active this by adding .active = true at the end of the code

orangeView.centerXAnchor.constraint(equalTo: view.centerXAnchor).active = true