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Start your free trialJonathan Law
iOS Development Techdegree Student 6,824 PointsDon't understand what I am doing wrong here. Error says I am not adding all the constraints from the question?
Can't understand what my error is here. Height, weight, a centerX and a centerY. I must be missing something....
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: view, attribute: .NotAnAttribute, multiplier: 1.0, constant: 50)
let sampleViewWidthConstraint = NSLayoutConstraint(item: sampleView, attribute: .Width, relatedBy: .Equal, toItem: view, attribute: .NotAnAttribute, multiplier: 1.0, constant: 50)
let sampleViewCenterXConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterX, relatedBy: .Equal, toItem: view, attribute: .CenterX, multiplier: 1.0, constant: 0)
let sampleViewCenterYConstraint = NSLayoutConstraint(item: sampleView, attribute: .CenterY, relatedBy: .Equal, toItem: view, attribute: .CenterY, multiplier: 1.0, constant: 0)
view.addConstraints ([sampleViewHeightConstraint,
sampleViewWidthConstraint,
sampleViewCenterXConstraint,
sampleViewCenterYConstraint])
}
}
1 Answer
Moritz Lang
25,909 PointsGlad that you figured it out already. Since iOS 9 there is a cleaner way to write LayoutConstraints. You could achieve the same result with the following code:
NSLayoutConstraint.activateConstraints([
sampleView.heightAnchor.constraintEqualToConstant(50.0),
sampleView.widthAnchor.constraintEqualToConstant(50.0),
sampleView.centerXAnchor.constraintEqualToAnchor(self.view.centerXAnchor),
sampleView.centerYAnchor.constraintEqualToAnchor(self.view.centerYAnchor)
])
This example is written in Swift 2.2. There are some changes in Swift 3, but they are easy to understand.
Jonathan Law
iOS Development Techdegree Student 6,824 PointsJonathan Law
iOS Development Techdegree Student 6,824 PointsI figured it out. Height and Width constraints should have toItem as nil, not "view."