Group A Dictionary By Key Value

No methods for grouping cannot be found in the Standard Library. You might need to do it yourself.

let dicts: [[String: AnyObject]] = [["order": 31399, "builder": "Test", "area": "North"], ["order": 4244, "builder": "Test", "area": "North"],["order": 41499, "builder": "new", "area": "South"]]
func groupByArea(acc: [String: [[String: AnyObject]]], elt: [String: AnyObject]) -> [String: [[String: AnyObject]]] {
    var result = acc
    let key = (elt["area"] as? String) ?? "*unspecified*"
    if result[key] == nil {
        result[key] = []
    }
    result[key]!.append(elt)
    return result
}
let grouped = dicts.reduce([:], combine: groupByArea)

Already more than answered my question, but if i was to want to go one more level in, i would just loop into this loop?

For Example group by area and in each area by builder.

in JSON example somthing like

["South": [["new": [[array of matching items]]], ["test": [[array of matching items]]], "North": [["new": [[array of matching items]]], ["test": [[array of matching items]]]

You need another strategy for the second level.

Before getting into it, groupByArea and groupByBuilder would be very similar, so having a function generator seems be a good way.

typealias GroupingFunc = ([String: [[String: AnyObject]]], [String: AnyObject]) -> [String: [[String: AnyObject]]]
func groupBy(keyName: String) -> GroupingFunc {
    return {acc, elt in
        var result = acc
        let key = (elt[keyName] as? String) ?? "*unspecified*"
        if result[key] == nil {
            result[key] = []
        }
        result[key]!.append(elt)
        return result
    }
}
let groupedByArea = dicts.reduce([:], combine: groupBy("area")) //same as `dicts.reduce([:], combine: groupByArea)`

With this, you can write something like this:

let dicts: [[String: AnyObject]] = [["order": 31399, "builder": "Test", "area": "North"], ["order": 4244, "builder": "Test", "area": "South"],["order": 41499, "builder": "new", "area": "South"]]
let groupedByArea = dicts.reduce([:], combine: groupBy("area"))
var groupedByAreaAndBuilder: [String: [String: [[String: AnyObject]]]] = [:]
for (area, subarray) in groupedByArea {
    groupedByAreaAndBuilder[area] = subarray.reduce([:], combine: groupBy("builder"))
}
print(groupedByAreaAndBuilder) //->["South": ["Test": [["order": 4244, "builder": Test, "area": South]], "new": [["order": 41499, "builder": new, "area": South]]], "North": ["Test": [["order": 31399, "builder": Test, "area": North]]]]

If you want to group by arbitrary multiple keys, that would be a little more complicated.

You have no idea how much you have helped me, THANK YOU!