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iOS Intermediate Swift Properties Property Observers

Sam Belcher
Sam Belcher
3,719 Points

I am confused. I have watched the videos over and over again and I still don't understand

also... Do you guys have any tips on code challenges in general? I feel like they have been becoming increasingly more dificult and its hard to keep up :/

class TemperatureController: UIViewController {
    var temperature: Double {
      didSet {
        switch self {
        case self > 80: view.backgroundColor = .red
        case self < 30: view.backgroundColor = .blue
        default: view.backgroundColor = .green

    init(temperature: Double) {
        self.temperature = temperature

    override func viewDidLoad() {
        view.backgroundColor = .white

1 Answer

Hi there,

You are switching on self - that's the UIViewController instance. Switch on self.temperature.

Then for your case statements, I'd use a local constant. Something like:

case let x where x < 40 : view.backgroundColor = .blue

I hope that helps,