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Start your free trialarnoldmukasa
3,924 PointsPlease Help! I can't seem to figure out where I'm wrong in this challenge
In the editor you've been provided with a UIViewController subclass that contains an instance of UIView, sampleView, as a stored property. You need to position and size sampleView by adding the following constraints: Height constraint of 50 points Width constraint of 50 points Center horizontally and vertically in container
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
])
}
}
Natalia Khachapuridze
5,579 PointsAlthough I just had a look again and when you create width and height constraints you need to put attribute: .notAnAttribute instead of attribute: .height That works
class MyViewController: UIViewController {
let sampleView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(sampleView)
}
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
sampleView.translatesAutoresizingMaskIntoConstraints = false
let sampleViewHeightConstraint = NSLayoutConstraint(item: sampleView, attribute: .height, relatedBy: .equal,
toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 50)
let sampleViewWidthConstraint = NSLayoutConstraint(item: sampleView, attribute: .width, relatedBy: .equal,
toItem: nil, attribute: .notAnAttribute, 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
])
}
}
1 Answer
kols
27,007 PointsNatalia was correct that you need to provide .notAnAttribute for the second attribute parameter in the height and width constraints; however, you'll also want to create a new method for setting up your constraints and call it separately instead of placing them in viewWillLayoutSubviews() (see setupSampleViewConstraints() method in the code below).
Hope that helps anyone who's having trouble with this!
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])
}
}
Natalia Khachapuridze
5,579 PointsNatalia Khachapuridze
5,579 PointsHey Arnold, I think that will work. If the issue is that you cant see the sample view it's because right now it has no colour. you could add a colour to test it:
override func viewDidLoad() { super.viewDidLoad()