How to loop over struct properties in Swift?

Question

Is it possible to iterate over properties of a struct in Swift?

I need to register cells-reuse identifiers in a view controller that makes use of many different cel

Answer 1

I made a recursive function based on @John R Perry's solution that goes deeper into properties that are objects. It also takes an parameter to limit how many levels deep it goes (default is Int.max) to help prevent stackoverflow's:

protocol Loopable {
    func allProperties(limit: Int) [String: Any]
}

extension Loopable {
    func allProperties(limit: Int = Int.max) [String: Any] {
        return props(obj: self, count: 0, limit: limit)
    }

    private func props(obj: Any, count: Int, limit: Int) -> [String: Any] {
        let mirror = Mirror(reflecting: obj)
        var result: [String: Any] = [:]
        for (prop, val) in mirror.children {
            guard let prop = prop else { continue }
            if limit == count {
                result[prop] = val
            } else {
                let subResult = props(obj: val, count: count + 1, limit: limit)
                result[prop] = subResult.count == 0 ? val : subResult
            }
        }
        return result
    }
}

I got rid of the check for if the object is a class or struct because that the parameter not being a class or struct is the base case of the recursive function, and it was easier to handle it manually than with errors.

Testing it:

class C {
    var w = 14
}
class B: Loopable {
    var x = 12
    var y = "BHello"
    var z = C()
    static func test() -> String {
        return "Test"
    }
}
class A: Loopable {
    var a = 1
    var c = 10.0
    var d = "AHello"
    var e = true
    var f = B()
    var g = [1,2,3,4]
    var h: [String: Any] = ["A": 0, "B": "Dictionary"]
    var i: Int?
}
print(A().allProperties())

prints:

["e": true, "g": [1, 2, 3, 4], "f": ["z": ["w": 14], "x": 12, "y": "BHello"], "h": ["A": 0, "B": "Dictionary"], "c": 10.0, "i": nil, "d": "AHello", "a": 1]

(Dictionaries are unordered, so if you get a different order, that's why)