check if any property in a struct is nil - Swift 4

Question

How to check that all properties of a struct are not nil, without knowing the number and types of the properties of this struct?

So, you may want to check this struct:

struct Fruit {
 var name: String?
 var fruitType: String?
 var quantity: Int?
}

and later another struct such as this one:

struct Farm {
 var name: String?
 var isOpen: Bool?
 var farmerName: String?
 var location: Location?
 var isCertified: Bool?
}

score 0 · Answer 1 · answered Jan 21 '18 at 18:42

0

protocol StructExt {
    func allPropertiesAreNotNull() throws -> Bool
}

extension StructExt {
    func allPropertiesAreNotNull() throws -> Bool {

        let mirror = Mirror(reflecting: self)

        return !mirror.children.contains(where: { $0.value as Any? == nil})
    }
}

Now testing for both structs should be done the following:

var fruit = Fruit() // Assuming with have an initializer for the struct
var farm = Farm() // Assuming with have an initializer for the struct
fruit.allPropertiesAreNotNull() // will return true or false depending on weither or not there is a nil property in that struct
farm.allPropertiesAreNotNull() // will return true or false depending on weither or not there is a nil property in that struct

answered Jan 21 '18 at 18:42

Stephane Paquet

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3

Returns `true` for `struct Fruit { var name: Int? = nil }` even though all properties *are* nil. – Martin R Jan 21 '18 at 18:53
See https://stackoverflow.com/a/44687935/1187415 for a working solution. – Martin R Jan 21 '18 at 19:04
Use `mirror.children.contains(where: { "\($0.value)" == "nil" })` worked for me – Izabella Melo Apr 13 '23 at 13:54

check if any property in a struct is nil - Swift 4

1 Answers1