How to generate random numbers without repetition in Swift? [duplicate]

Answer 1

You can create a function that returns a random-number generating closure, like this:

func randomSequenceGenerator(min: Int, max: Int) -> () -> Int {
    var numbers: [Int] = []
    return {
        if numbers.isEmpty {
            numbers = Array(min ... max)
        }

        let index = Int(arc4random_uniform(UInt32(numbers.count)))
        return numbers.remove(at: index)
    }
}

To use it, first call the generator once to create the random sequence generator, then call the return value as many times as you like. This will print out random values between one and six, cycling through all of them before starting over:

let getRandom = randomSequenceGenerator(min: 1, max: 6)
for _ in 1...20 {
    print(getRandom())
}