How can I pick three random elements out of a dictionary in Swift 4.1 - swift

Question

I am having a problem picking three random elements out of a dictionary.
My dictionary code:
query.observeSingleEvent(of: .value, with: { snapshot in
for child in snapshot.children {
let childSnap = child as! DataSnapshot
var dict = childSnap.value as! [String: Any]
}
})

Answer 1

You can use an array if keys are integers.
if you want to use a dictionary only then below mentioned code might be helpful for you
var namesOfPeople = [Int: String]()
namesOfPeople[1] = "jacob"
namesOfPeople[2] = "peter"
namesOfPeople[3] = "sam"
func makeList(n: Int) -> [Int] {
print(namesOfPeopleCount)
return (0..<n).map { _ in namesOfPeople.keys.randomElement()! }
}
let randomKeys = makeList(3)
You can try this for older version Of Swift where randomElement() is not available
let namesOfPeopleCount = namesOfPeople.count
func makeList(n: Int) -> [Int] {
return (0..<n).map{ _ in Int(arc4random_uniform(namesOfPeopleCount)
}

Answer 2

#Satish answer is fine but here's one which is a bit more complete and selects a random user from a list of users loaded from Firebase ensuring a user is only selected once.
We have have an app with two buttons
populateArray
selectRandomUser
and we have a UserClass to store our user data for each user.
class UserClass {
var uid = ""
var name = ""
init(withSnapshot: DataSnapshot) {
let dict = withSnapshot.value as! [String: Any]
self.uid = withSnapshot.key
self.name = dict["Name"] as! String
}
}
and an array to store the users in
var userArray = [UserClass]()
When the populateArray button is clicked this code runs
func populateArray() {
let usersRef = self.ref.child("users")
usersRef.observeSingleEvent(of: .value, with: { snapshot in
for child in snapshot.children {
let snap = child as! DataSnapshot
let user = UserClass(withSnapshot: snap)
self.userArray.append(user)
}
print("array populated")
})
}
and then to select a random user use this code.
func selectRandomUser() {
if let someUser = userArray.randomElement() {
print("your random user: \(someUser.name)")
let uid = someUser.uid
if let index = userArray.index(where: { $0.uid == uid } ) {
userArray.remove(at: index)
}
} else {
print("no users remain")
}
}
This code ensures the same user is not selected twice. Note that this is destructive to the array containing the users so if that's unwanted, make a copy of the array after it's populated and work with that.