Find Missing Numbers

func findDisappearedNumbers(_ nums: inout [Int]) -> [Int] {
    var outputArr = [Int]()
    let numsCount = nums.count
    guard let minNum = nums.min(),
        let maxNum = nums.max()
        else { return [] }
    let range = minNum...maxNum
    if numsCount == range.count {
        return []
    }
    for (index, rangeNum) in range.enumerated() {
        if index < nums.count {
            print("rangeNum:", rangeNum)
            print("nums at index:", nums[index])
            if rangeNum != nums[index] {
                nums.insert(rangeNum, at: index)
                print("new nums at index:", nums[index])
                print("nums at index +1:", nums[index + 1])
                outputArr.append(rangeNum)
            }
        }
    }
    return outputArr
}
var numsToTest = [1,2,3,5,6,8]
findDisappearedNumbers(&numsToTest)