Similar to key-path way to access values in swift dictionary

Swift-dictionary-key-path-access.swift

import Foundation

extension Dictionary {
    func JSONValue(path:String) -> AnyObject? {
        let dict = self as! NSDictionary
        return dict.JSONValue(path)
    }
}

extension NSDictionary {
    private func arrayIndex(comp:String) -> (String, String?)? {
        let opn = NSStringCompareOptions.BackwardsSearch
        let rng = comp.fullRange
        guard let start = comp.rangeOfString("[", options: opn, range: rng),
            end = comp.rangeOfString("]", options: opn, range: rng) else {
            return nil
        }
        let name = comp.substringToIndex(start.startIndex)
        let index = comp.substringWithRange(start.startIndex.advancedBy(1) ..< end.endIndex.advancedBy(-1))
        return (name, index)
    }

    func JSONArray(dict:[String:AnyObject], name:String, index:String?) -> AnyObject? {
        if let ind = Int(index!) {
            return (dict[name] as? [AnyObject])?[ind]
        }
        return nil
    }

    func JSONValue(path:String) -> AnyObject? {
        var dict:AnyObject = self
        var components = path.componentsSeparatedByString(".")
        guard let last = components.last else { return nil }
        if components.count >= 1 {
            components = Array(components.dropLast(1))
        }

        for comps in components {
            if let arrIndex = arrayIndex(comps) {
                dict = JSONArray(dict as! [String : AnyObject], name:arrIndex.0, index: arrIndex.1)!
            } else {
                if let dict1 = dict[comps] as? [String:AnyObject] {
                    dict = dict1
                }
            }
        }

        if let arrIndex = arrayIndex(last) {
            return JSONArray(dict as! [String : AnyObject], name:arrIndex.0, index: arrIndex.1)!
        } else {
            return (dict as? [String:AnyObject])?[last]
        }
    }
}

extension String {
    var fullRange: Range<String.Index> {
        return self.startIndex ..< self.endIndex
    }
}



// usage + test
let testData = [ "one":
    [ "two":
        [
            "four":4,
            "three":["hello", "how", "are"]]
    ],
    "boo": [1, 2, "bosob", 4],
    "arr_obj": [ ["one":1, "two":2], ["two":2, "three":3], ["four":4, "three":3] ]
]

testData.JSONValue("arr_obj[0].one") 	// 1
testData.JSONValue("arr_obj[0].one") 	// 1
testData.JSONValue("arr_obj[0].two") 	// 2
testData.JSONValue("arr_obj[1].two") 	// 2
testData.JSONValue("arr_obj[1].three") 	// 3
testData.JSONValue("arr_obj[2].three") 	// 3
testData.JSONValue("arr_obj[2].four") 	// 4
testData.JSONValue("one")
// {
//two =     {
//    four = 4;
//    three =         (
//        hello,
//        how,
//        are
//    );
//};
//}
testData.JSONValue("one.two")
// {
//four = 4;
//three =     (
//    hello,
//    how,
//    are
//);
//}
testData.JSONValue("one.two.four") 	// 4
testData.JSONValue("one.two.three")
// (
//hello,
//how,
//are
//)
testData.JSONValue("one.two.three[0]") 	// hello
testData.JSONValue("one.two.three[1]") 	// how
testData.JSONValue("one.two.three[2]") 	// are
testData.JSONValue("boo")
// (
//  1,
//  2,
//  bosob,
//  4
//)
testData.JSONValue("boo[0]") 	// 1
testData.JSONValue("boo[1]") 	// 2
testData.JSONValue("boo[2]") 	// bosob
testData.JSONValue("boo[3]") 	// 4
testData.JSONValue("")          // nil