custom datasource method is not calling in swift 2.0 - swift2

Question

here is my BorderView and The task I'm trying to do is to hookup the custom object (Border) to the main storyboard.
import UIKit
protocol BorderViewDataSource: class{
func colorForBorderView(sender:BorderView) -> String? }
class BorderView: UIView {
#IBOutlet weak var topLeftImage: UIImageView!
#IBOutlet weak var topRightImage: UIImageView!
#IBOutlet weak var bottomLeftImage: UIImageView!
#IBOutlet weak var bottomRightImage: UIImageView!
var view: UIView!
weak var dataSource:BorderViewDataSource?
override init(frame: CGRect) {
super.init(frame: frame)
xtraSetup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
xtraSetup()
}
func xtraSetup() {
view = loadViewFromNib()
// use bounds not frame or it'll be offset
view.frame = bounds
// Make the view stretch with containing view
view.autoresizingMask = [UIViewAutoresizing.FlexibleWidth, UIViewAutoresizing.FlexibleHeight]
// Adding custom subview on top of our view (over any custom drawing > see note below)
addSubview(view)
let borderColor = dataSource?.colorForBorderView(self) ?? "red"
applyColor(borderColor)
}
// this is an actual load from nib module
func loadViewFromNib() -> UIView {
let bundle = NSBundle(forClass: self.dynamicType)
let nib = UINib(nibName: "BorderView", bundle: bundle)
let view = nib.instantiateWithOwner(self, options: nil)[0] as! UIView
return view
}
func applyColor(borderColor:String){
var imageName = "border-topleft-\(borderColor)"
topLeftImage.image = UIImage(named: imageName)
imageName = "border-topright-\(borderColor)"
print("Border color is \(borderColor), and Last image name is \(imageName)")
}
}
So when i open the app it will show the image of different color depending on what the value of the color is set in the ViewContorller.swift and here is my viewcontroller. swift code
class ViewController: UIViewController, BorderViewDataSource {
var borderType = 2
#IBOutlet weak var borderView: BorderView!{
didSet{
borderView.dataSource = self
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func colorForBorderView(sender: BorderView) -> String? {
var borderColor = "blue"
switch borderType {
case 1: borderColor = "blue"
case 2: borderColor = "purple"
case 3: borderColor = "red"
default: break
}
print("Border Type is \(borderType), and border color is \(borderColor)")
return borderColor
}
}
but colorForBorderView method is not calling when i running the app

Answer 1

It seems when the view is initialized, the dataSource property of that view is nil. And you only call that method during initialization of your view. You can apply the color after viewDidLoad() in your view controller

Answer 2

From the documentation:
When you assign a default value to a stored property, or set its
initial value within an initializer, the value of that property is set
directly, without calling any property observers.
That's the reason why the datasource is not set. Put the line borderView.dataSource = self into viewDidLoad()