dependencies.swift

let keys = [
    1 : ["value" : "FirstValue", "dependencies" : Set(arrayLiteral: 2)],
    2 : ["value" : "SecondValue", "dependencies" : Set(arrayLiteral: 1)],
]

keys.reduce(Dictionary<Set<Int>, Set<Int>>()) { (allDependencies, keyValueTuple) in
    let (key, content) = keyValueTuple
    var dependencyGraph = allDependencies
    
    let dependencyKey = (content["dependencies"] as! Set<Int>).union([key])
    dependencyGraph[dependencyKey] = dependencyGraph[dependencyKey]?.union([key]) ?? [key]
    
    
    if dependencyGraph[dependencyKey] == dependencyKey {
        print("Dependency has been fulfilled for \(key) with list \(dependencyGraph[dependencyKey])")
    }
    else {
        print("Dependency is not fulfilled yet for key: \(key)")

    }
    
    return dependencyGraph
}