CODEWITHSUNDEEP
swiftconstantskeychain
Laurence Wingo
Laurence Wingo

Reputation: 3952

What is the purpose of using static on a constant in a Swift structure?

While following a tutorial on using the Keychain feature, I noticed a section of code where I needed to implement a structure as the following: 

// Keychain Configuration
struct KeychainConfiguration {
  static let serviceName = "TouchMeIn"
  static let accessGroup: String? = nil
}

I know that a constant property on a value type can't be modified once instantiated so I was curious of the purpose of using static in this sense?


P.S.
This question is not similar to this question because the highest accepted answer (which I would think is the best answer) doesn't provide enough detail or any pros or cons.

Upvotes: 1

Views: 145

Answers (1)

fewlinesofcode
fewlinesofcode

Reputation: 3082

It has multiple applications, including but not limited by the following:

1) To give a constant separate namespace, if constants have same names. 

struct A {
    static let width: Int = 100
}

struct B {
    static let width: Int = 100
}
print(A.width)
print(B.width)

2) Static constants are 'lazy' by design, so if you are about to use lazy-behaved global constant, it might be handy to put it in a structure.

3) To show your coworkers that constant is applicable to specific domain where given structure is used.

4) Organize your configuration in sections:Theme.Layout.itemHeight or Label.Font.avenirNext

Upvotes: 2

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