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iOS

Colin Warn
Colin Warn
6,358 Points
Posted by Colin Warn
Colin Warn
6,358 Points

Constraints in Code, What Am I Missing?

Trying to add constraints into my code for the Intro to Autolayout challenge. Using the .height, .width, .centerX and .centerY attributes, yet it's saying I'm putting in the wrong attributes. Any idea what's wrong?

Code: let height = NSLayoutConstraint(item: sampleView, attribute: .height, relatedBy: .equal, toItem: self, attribute: .height, multiplier: 1.0, constant: 50.0)

    let width = NSLayoutConstraint(item: sampleView, attribute: .width, relatedBy: .equal, toItem: self, attribute: .width, multiplier: 1.0, constant: 50)

    let verticalConstraint = NSLayoutConstraint(item: sampleView, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 1.0)

    let horizontalContraint = NSLayoutConstraint(item: sampleView, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 1.0)


    // Add constraints below
    view.addConstraints([height,
                        width,
                        verticalConstraint,
                        horizontalContraint])

1 Answer

Christian Mangeng
Christian Mangeng
15,970 Points
Christian Mangeng
Christian Mangeng
15,970 Points

Hi Colin,

that's how I did it:

let height = NSLayoutConstraint(item: sampleView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)
let width = NSLayoutConstraint(item: sampleView, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)
let centerHor = NSLayoutConstraint(item: sampleView, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 0.0)
let centerVer = NSLayoutConstraint(item: sampleView, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1.0, constant: 0.0)

Note that width and height do not refer to any other item, so put nil and .notAnAttribute for toItem and the second attribute argument, respectively. Also, make sure to set the constant in width to 50.0, not the int value 50. It expects a float value input.