Type Properties in Extensions

Question

Created Jul ’22

Replies 2

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Participants 3

I am new to Swift, and I have been following a tutorial on Creating a Card View. In Section 2, step 3, it directs the user to add an extension to the DailyScrum struct:

struct DailyScrum {
  var title: String
  var attendees: [String]
  var lengthInMinutes: Int
  var theme: Theme
}

extension DailyScrum {
  static let sampleData: [DailyScrum] =
  [
    DailyScrum(...),
    DailyScrum(...),
    DailyScrum(...)
  ]
}

From my understanding, the constant sampleData is a stored type property, yet I read that extensions can only add computed type properties. Can someone help me understand what sampleData is, and why it can be used in an extension?

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Answer 1

robnotyou OP

Jul ’22

sampleData is an array of DailyScrum.
It is a "let" constant, it cannot be changed.

It is a computed property... it is computed at compile time.

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Answer 2

Claude31 OP

Jul ’22

sampleData is not an instance property but a type property. That's why you can use it.

A computed property would be

var sampleData: [DailyScrum] {  [
    DailyScrum(...),
    DailyScrum(...),
    DailyScrum(...)
  ] }

The reason is explained here: https://www.reddit.com/r/swift/comments/7trzca/whats_the_reasoning_for_extensions_may_not/

0