How do I check if an object is a collection? (Swift)

Collection can no longer be used for type-checking, hence Ahmad F's solution would no longer compile.

I did some investigation. Some people advice to bridge to obj-c collections and use isKindOfClass, others try to employ reflection (by using Mirror). Neither is satisfactory.

There's a pretty straight-forward, a bit rough yet efficient way to accomplish the task via splitting object type if our concern is Array, Dictionary or Set (list can be updated):

func isCollection<T>(_ object: T) -> Bool {
    let collectionsTypes = ["Set", "Array", "Dictionary"]
    let typeString = String(describing: type(of: object))

    for type in collectionsTypes {
        if typeString.contains(type) { return true }
    }
    return false
}

Usage:

var set : Set! = Set<String>()
var dictionary : [String:String]! = ["key" : "value"]
var array = ["a", "b"]
var int = 3
isCollection(int) // false
isCollection(set) // true
isCollection(array) // true
isCollection(dictionary) // true

Hard-code is the drawback but it does the job.

NOTE: This solution does NOT work with Swift 5+.

func isCollection<T>(object: T) -> Bool {
    switch object {
    case _ as Collection:
        return true
    default:
        return false
    }
}

Calling:

// COLLECTION TESTING //

let arrayOfInts = [1, 2, 3, 4, 5]
isCollection(object: arrayOfInts) // true

let setOfStrings:Set<String> = ["a", "b", "c"]
isCollection(object: setOfStrings) // true

// [String : String]
let dictionaryOfStrings = ["1": "one", "2": "two", "3": "three"]
isCollection(object: dictionaryOfStrings) // true


// NON-COLLECTION TESTING //

let int = 101
isCollection(object: int) // false

let string = "string" // false

let date = Date()
isCollection(object: date) // false