ios - How can I create a static computed property that computes only once? -

i've created computed static property i'd have computed once , whenever accessed after return original computed value. lazy properties appear want after bit of searching appears static properties lazy default.

when run following code comes out fine first time accessed/ if run each unit test individually. when access 2nd time i'm given empty array.

static var att: [conferencenumber] = {     let list = builddirectory(for: .att, from: jsonarray)     return list }()  private static let jsonarray: [any]? = {     let numbersfilepath = bundle.main.path(forresource: "numbers", oftype:"json")     let data = try! data(contentsof: url(fileurlwithpath:numbersfilepath!), options: .uncached)      return try! jsonserialization.jsonobject(with: data) as? [any] }() 

code called 2nd time , returns empty array

private static func isattmeeting(meetingtext: string, parsedphonenumbers: [string]) -> bool {     let attphonenumbers = conferencenumberdirectory.att.map{$0.number}     let attnumberwasparsed = parsedphonenumbers.intersects(with: attphonenumbers)     if attnumberwasparsed {         return true     }     return meetingtext.contains(pattern: atturlregex) || meetingtext.contains(pattern: atturlregex2) } 

your solution should work. maybe there wrong other part of code. take @ following example:

var mystrings = ["a", "b"]  class someclass {     static let strings: [string] = {         return mystrings     }() }  print("mystrings: \(mystrings)") print("static strings: \(someclass.strings)")  mystrings.append("c")  print("mystrings: \(mystrings)") print("static strings: \(someclass.strings)") 

prints:

mystrings: ["a", "b"] static strings: ["a", "b"] mystrings: ["a", "b", "c"] static strings: ["a", "b"] 

so following piece of code should work:

class conferencenumberdirectory {     static let att: [conferencenumber] = {         return builddirectory(for: .att, from: jsonarray)     }() }