Performance fix: created two valueFor functions (one for dictionaries…

… and one for arrays) to remove the need to cast the JSON dictionary input

Casting the dictionary was very slow especially given a large JSON input

ObjectMapper/Core/Map.swift

@@ -63,7 +63,7 @@ public final class Map {
 			currentValue = JSONDictionary[key]
 		} else {
 			// break down the components of the key that are separated by .
-			currentValue = valueFor(ArraySlice(key.componentsSeparatedByString(".")), collection: JSONDictionary)
+			currentValue = valueFor(ArraySlice(key.componentsSeparatedByString(".")), dictionary: JSONDictionary)
 		}
 
 		return self
@@ -101,44 +101,50 @@ public final class Map {
 	}
 }
 
-/// Fetch value from JSON dictionary, loop through them until we reach the desired object.
-private func valueFor(keyPathComponents: ArraySlice<String>, collection: AnyObject?) -> AnyObject? {
+/// Fetch value from JSON dictionary, loop through keyPathComponents until we reach the desired object
+private func valueFor(keyPathComponents: ArraySlice<String>, dictionary: [String: AnyObject]) -> AnyObject? {
 	// Implement it as a tail recursive function.
-
 	if keyPathComponents.isEmpty {
 		return nil
 	}
 
-	//optional object to keep optional retreived from collection
-	var optionalObject: AnyObject?
+	if let keyPath = keyPathComponents.first {
+		let object = dictionary[keyPath]
+		if object is NSNull {
+			return nil
+		} else if let dict = object as? [String : AnyObject] where keyPathComponents.count > 1 {
+			let tail = keyPathComponents.dropFirst()
+			return valueFor(tail, dictionary: dict)
+		} else {
+			return object
+		}
+	}
 
-	//check if collection is dictionary or array (if it's array, also try to convert keypath to Int as index)
-	if let dictionary = collection as? [String : AnyObject],
-		let keyPath = keyPathComponents.first {
+	return nil
+}
 
-		//keep retreved optional
-		optionalObject = dictionary[keyPath]
-	} else if let array = collection as? [AnyObject],
-		let keyPath = keyPathComponents.first,
-		index = Int(keyPath) {
-
-		//keep retreved optional
-		optionalObject = array[index]
+/// Fetch value from JSON Array, loop through keyPathComponents them until we reach the desired object
+private func valueFor(keyPathComponents: ArraySlice<String>, dictionary: [AnyObject]) -> AnyObject? {
+	// Implement it as a tail recursive function.
+
+	if keyPathComponents.isEmpty {
+		return nil
 	}
 
-	if let object = optionalObject {
+	//Try to convert keypath to Int as index)
+	if let keyPath = keyPathComponents.first,
+		let index = Int(keyPath) {
+
+		let object = dictionary[index]
+
 		if object is NSNull {
 			return nil
-		} else if let dict = object as? [String : AnyObject] where keyPathComponents.count > 1 {
-			let tail = keyPathComponents.dropFirst()
-			return valueFor(tail, collection: dict)
 		} else if let dict = object as? [AnyObject] where keyPathComponents.count > 1 {
 			let tail = keyPathComponents.dropFirst()
-			return valueFor(tail, collection: dict)
+			return valueFor(tail, dictionary: dict)
 		} else {
 			return object
 		}
 	}
-
 	return nil
 }