How to generate a random number in Swift without repeating the previous random number?

Solution 1:

my solution, i think its easy to understand

var nums = [0,1,2,3,4,5,6,7,8,9]

while nums.count > 0 {

    // random key from array
    let arrayKey = Int(arc4random_uniform(UInt32(nums.count)))

    // your random number
    let randNum = nums[arrayKey] 

    // make sure the number isnt repeated
    nums.swapAt(arrayKey, nums.count-1)
    nums.removeLast()
}

Solution 2:

Store the previous generated number in a variable and compare the generated number to the previous number. If they match generate a new random number. Repeat the generation of new numbers until they don't match.

var previousNumber: UInt32? // used in randomNumber() 

func randomNumber() -> UInt32 {
    var randomNumber = arc4random_uniform(10)
    while previousNumber == randomNumber {
        randomNumber = arc4random_uniform(10)
    }
    previousNumber = randomNumber
    return randomNumber
}