Function returning the first non-iterative value from an array

gistfile1.txt

import Foundation

var array = [1,2,1,3,5]

func arrayCalculation(_ array: [Int]) -> Int {
    
    var dictionary: [Int:Int] = [:]
    var sortedArray: [Int] = []
    
    // With this portion of the code, I'm iterating over the array and adding the dictionary items to an array
    for item in array {
        dictionary[item] = (dictionary[item] ?? 0) + 1
    }
    
    //From here, I'm sorting the array of objects based on their key value, I chose this method since the original array is in ascending order, but the sort method might have to change based on the array type
    let sorted = dictionary.sorted(by: {$0.key < $1.key}) 
    
    // At this point, I'm appending the keys from the sorted dictionary that match a value of 1, making it so they are non-iterative
    for item in sorted {
        if item.value == 1 {
            sortedArray.append(item.key)
        }
    } 
    //Returning the key value of the first non-iterative value which should be 2
    return sortedArray.first! 
}

arrayCalculation(array) // Calling the function