Make an array from values belonging to a specific key in a dictionary (Swift 4)

I'm experimenting with dictionaries in Swift 4. I'm trying to make an array from a couple of values belonging to a randomly picked key within a dictionary. I'm not exactly sure how I need to do this in Swift 4.

//: Dictionary Test 

import UIKit

var database = ["Albert Einstein": ["Alberts first quote",
                                    "Alberts second quote",
                                    "Alberts third quote"],

                     "Martin Luther King": ["Martin's first quote",
                                            "Martin's second quote",
                                            "Martin's third quote"],

                     "Newton": ["Newton's first quote",
                                "Newton's second quote",
                                "Newton's third quote"]]

func randomQuote(){
    //Make an array from database keys
    var authorArray = Array(database.keys)

    //Pick a random author
    let author = (authorArray[Int(arc4random_uniform(UInt32(authorArray.count)))])

    //Make an array from values based on the author we've picked (HERE'S THE PROBLEM)
    let quoteArray = Array(database[author].values)

    //Pick a random quote from the choses author
    let quote = (quoteArray[Int(arc4random_uniform(UInt32(quoteArray.count)))])

    print(author)
    print(quote)
}

randomQuote()

Now obviously let quoteArray = Array(database[author].values) is not working. Anyone an idea how this would work?