How to access deeply nested dictionaries in Swift

Question

I have a pretty complex data structure in my app, which I need to manipulate. I am trying to keep track of how many types of bugs a player has in thier garden. There are te

Answer 1

Yet another approach using various overloaded Dictionary subscript implementations:

let dict = makeDictionary(fromJSONString:
        """
        {
            "control": {
                "type": "Button",
                "name": "Save",
                "ui": {
                    "scale": 0.5,
                    "padding": {
                        "top": 24,
                        "bottom": 32
                    }
                }
            }
        }
        """)!

dict[Int.self, ["control", "ui", "padding", "top"]] // 1
dict[Int.self, "control", "ui", "padding", "top"]   // 2
dict[Int.self, "control.ui.padding.top"]        // 3

And the actual implementations:

extension Dictionary {
    // 1    
    subscript(_ type: T.Type, _ pathKeys: [Key]) -> T? {
        precondition(pathKeys.count > 0)

        if pathKeys.count == 1 {
            return self[pathKeys[0]] as? T
        }

    // Drill down to the innermost dictionary accessible through next-to-last key
        var dict: [Key: Value]? = self
        for currentKey in pathKeys.dropLast() {
            dict = dict?[currentKey] as? [Key: Value]
            if dict == nil {
                return nil
            }
        }

        return dict?[pathKeys.last!] as? T
    }

    // 2. Calls 1
    subscript(_ type: T.Type, _ pathKeys: Key...) -> T? {
        return self[type, pathKeys]
    }
}

extension Dictionary where Key == String {
    // 3. Calls 1
    subscript(_ type: T.Type, _ keyPath: String) -> T? {
        return self[type, keyPath.components(separatedBy: ".")]
    }
}

func makeDictionary(fromJSONString jsonString: String) -> [String: Any]? {
    guard let data = jsonString.data(using: .utf8)
        else { return nil}
    let ret = try? JSONSerialization.jsonObject(with: data, options: [])
    return ret as? [String: Any]
}