CODEWITHSUNDEEP
iosswift
Dave
Dave

Reputation: 12206

Is This a Variable or a Function? Or Both?

I'm following this tutorial and the starter project includes a UITableViewCell class with this code:

var product: SKProduct? {
  didSet {
    guard let product = product else { return }

    textLabel?.text = product.localizedTitle

    if RageProducts.store.isProductPurchased(product.productIdentifier) {
      accessoryType = .checkmark
      accessoryView = nil
      detailTextLabel?.text = ""
    } else {
      ProductCell.priceFormatter.locale = product.priceLocale
      detailTextLabel?.text = ProductCell.priceFormatter.string(from: product.price)

      accessoryType = .none
      accessoryView = newBuyButton()
    }
  }
}

This looks like a function without parameters. I've never seen a variable with an enclosure before. The first line is a var statement but starts an enclosure:

var product: SKProduct? {

Can anyone explain this?

Upvotes: 0

Views: 65

Answers (1)

Kevin Aleman
Kevin Aleman

Reputation: 393

In this example, product is a variable, and didSet is a function. More specifically, didset is a property observer. From Apple's documentation:

Property observers observe and respond to changes in a property’s value. Property observers are called every time a property’s value is set, even if the new value is the same as the property’s current value.

So the code inside of didSet will get executed any time you make a variable assignment, like:

product = someSKProduct

Upvotes: 3

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