Element Frequency: Find the values in an array with a given frequency

FrequencyElements.swift

/// Find the values in an array with a given frequency
///
/// - Parameters:
///   - array: the array to search through
///   - k: the frequency value
/// - Returns: an array of values with the corresponding frequency
func frequency(for array: [Int], k: Int) -> [Int] {
   
    var bucket: [[Int]] = []
    var frequency: [Int:Int] = [:]

    array.enumerated().forEach { offset, element in
        if let val = frequency[element] {
            frequency[element] = val + 1
        } else {
            frequency[element] = 1
        }
        
        bucket.insert([], at: offset)
    }
    
    frequency.forEach { key, value in
        bucket[value].append(key)
    }

    print(frequency)
    return bucket[k]
}

let input = [1, 3, 4, 4, 3, 5, 6, 2, 1, 1, 5]
let bucket = frequency(for: input, k: 2)

print("bucket here \(bucket)")
// bucket here [4, 5, 3]