draw line in place of x axis in view controller - swift

Question

I want my swift code to draw a line like the place of a x axis. So the line is in the center of the screen no matter what screen size the object is displayed in. My code below produces a line but it does not account for the device size. My image below displays a black line which is what my current code produces and the orange line is the desired output.
Pic
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let lineView = UIView(frame: CGRect(x: 0, y: 100, width: 320, height: 1.0))
lineView.layer.borderWidth = 1.0
lineView.layer.borderColor = UIColor.black.cgColor
self.view.addSubview(lineView)
}
}

Answer 1

To draw a line in the middle of the screen, just assign the Line.swift file to UIView on which you want to draw a line.
Line.swift file
class Line:UIView {
var line = UIBezierPath()
func drawLine() {
line.move(to: CGPoint(x: 0, y: bounds.height / 2))
line.addLine(to: CGPoint(x: (bounds.width) , y: bounds.height / 2))
UIColor.black.setStroke()
line.lineWidth = 0.1
line.stroke()
}
override func draw(_ rect: CGRect) {
drawLine()
}
}
To assign it to your UIView, open the main.storyboard and click on the view where you want to draw the line. Then, go into upper right tabs which would look like this
You can see inside the class field, there is a placeholder called "UIView". Type there Line and hit enter, and then just run the project. You 'll be able to see the line in the middle of the view. No need to declare or call any function. Just assign this class and run the project.

Answer 2

If you want to respond with the width of the view, you can use constraints:
override func viewDidLoad() {
super.viewDidLoad()
let lineView = UIView()
lineView.translatesAutoresizingMaskIntoConstraints = false
lineView.layer.borderWidth = 1
lineView.layer.borderColor = UIColor.black.cgColor
view.addSubview(lineView)
NSLayoutConstraint.activate([
lineView.leftAnchor.constraint(equalTo: view.leftAnchor),
lineView.rightAnchor.constraint(equalTo: view.rightAnchor),
lineView.topAnchor.constraint(equalTo: view.topAnchor, constant: 100),
lineView.heightAnchor.constraint(equalToConstant: 1)
])
}
For what it’s worth, rather than drawing lines using the border of a view, I'd define a UIBezierPath and use that for a CAShapeLayer’s path:
#IBDesignable
class GraphView: UIView {
let shapeLayer: CAShapeLayer = {
let shapeLayer = CAShapeLayer()
shapeLayer.lineWidth = 2
shapeLayer.strokeColor = UIColor.black.cgColor
shapeLayer.fillColor = UIColor.clear.cgColor
return shapeLayer
}()
override init(frame: CGRect = .zero) {
super.init(frame: frame)
layer.addSublayer(shapeLayer)
}
required init?(coder: NSCoder) {
super.init(coder: coder)
layer.addSublayer(shapeLayer)
}
override func layoutSubviews() {
super.layoutSubviews()
let path = UIBezierPath()
path.move(to: CGPoint(x: bounds.minX, y: 100))
path.addLine(to: CGPoint(x: bounds.maxX, y: 100))
shapeLayer.path = path.cgPath
}
}
Then you can add this view to your view hierarchy like shown above, or right in Interface Builder (obviously, defining the constraints in IB, too).