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Start your free trialGreg Kaleka
39,021 PointsAdding Constraints in Code
Really not sure what the problem is here. I've created and added all four constraints, but I'm getting the error
Bummer! Make sure you have the correct constraints. One for height, one for width, one for CenterX and one for CenterY
class MyViewController: UIViewController {
let sampleView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(sampleView)
}
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
sampleView.translatesAutoresizingMaskIntoConstraints = false
// Add constraints below
let sampleViewHeightConstraint = NSLayoutConstraint(item: sampleView, attribute: .Height, relatedBy: .Equal,
toItem: nil, attribute: .Height, multiplier: 1, constant: 50)
let sampleViewWidthConstraint = NSLayoutConstraint(item: sampleView, attribute: .Width, relatedBy: .Equal,
toItem: nil, attribute: .Width, multiplier: 1, constant: 50)
let sampleViewCenterXConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterX, relatedBy: .Equal,
toItem: view, attribute: .CenterX, multiplier: 1, constant: 0)
let sampleViewCenterYConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterY, relatedBy: .Equal,
toItem: view, attribute: .CenterY, multiplier: 1, constant: 0)
view.addConstraints([
sampleViewHeightConstraint,
sampleViewWidthConstraint,
sampleViewCenterXConstraint,
sampleViewCenterYConstraint
])
}
}
Greg Kaleka
39,021 PointsThanks Terrell. Unfortunately, that did not fix the problem.
class MyViewController: UIViewController {
let sampleView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(sampleView)
}
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
sampleView.translatesAutoresizingMaskIntoConstraints = false
// Add constraints below
let sampleViewHeightConstraint = NSLayoutConstraint(item: sampleView, attribute: .Height, relatedBy: .Equal,
toItem: nil, attribute: .Height, multiplier: 1.0, constant: 50.0)
let sampleViewWidthConstraint = NSLayoutConstraint(item: sampleView, attribute: .Width, relatedBy: .Equal,
toItem: nil, attribute: .Width, multiplier: 1.0, constant: 50.0)
let sampleViewCenterXConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterX, relatedBy: .Equal,
toItem: view, attribute: .CenterX, multiplier: 1.0, constant: 0.0)
let sampleViewCenterYConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterY, relatedBy: .Equal,
toItem: view, attribute: .CenterY, multiplier: 1.0, constant: 0.0)
view.addConstraints([
sampleViewHeightConstraint,
sampleViewWidthConstraint,
sampleViewCenterXConstraint,
sampleViewCenterYConstraint
])
}
}
1 Answer
Chris Adamson
132,143 PointsThis is a tricky one, you were close the attribute is .NotAnAttribute for the 2nd item in the constraint:
class MyViewController: UIViewController {
let sampleView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(sampleView)
}
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
sampleView.translatesAutoresizingMaskIntoConstraints = false
// Add constraints below
let sampleViewHeightConstraint = NSLayoutConstraint(item: sampleView, attribute: .Height, relatedBy: .Equal,
toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 50.0)
let sampleViewWidthConstraint = NSLayoutConstraint(item: sampleView, attribute: .Width, relatedBy: .Equal,
toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 50.0)
let sampleViewCenterXConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterX, relatedBy: .Equal,
toItem: view, attribute: .CenterX, multiplier: 1.0, constant: 0.0)
let sampleViewCenterYConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterY, relatedBy: .Equal,
toItem: view, attribute: .CenterY, multiplier: 1.0, constant: 0.0)
view.addConstraints([sampleViewHeightConstraint,sampleViewWidthConstraint,sampleViewCenterXConstraint,sampleViewCenterYConstraint])
}
}
kols
27,007 PointsChris Adamson is correct just with the exception that — as of this time (Swift 4) — the member values provided for the 'attribute' parameters (e.g., attribute: .centerX) need to be lowerCamelCase. (Adding full code below for reference / ease.)
class MyViewController: UIViewController {
let sampleView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(sampleView)
}
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
sampleView.translatesAutoresizingMaskIntoConstraints = false
// Add constraints below
setupSampleViewConstraints()
}
func setupSampleViewConstraints() {
let sampleViewCenterXConstraint = NSLayoutConstraint(item: sampleView, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 0.0)
let sampleViewCenterYConstraint = NSLayoutConstraint(item: sampleView, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1.0, constant: 0.0)
let sampleViewHeightConstraint = NSLayoutConstraint(item: sampleView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)
let sampleViewWidthConstraint = NSLayoutConstraint(item: sampleView, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)
view.addConstraints([sampleViewCenterXConstraint, sampleViewCenterYConstraint, sampleViewHeightConstraint, sampleViewWidthConstraint])
}
}
Terrell Robinson
6,957 PointsTerrell Robinson
6,957 PointsHey Greg!
Not sure if you completed this since you posted this question, but the only error that I see is that your multipliers and constant fields aren't doubles. i.e. (multiplier: 1.0, constant: 50.0)
Try that out and it should work!