Unwrap from JSON dict with default value

unwrap.swift

func unwrap<T:Any>(dictionary:[String : AnyObject], key:String, defaultValue:T) -> T {
        let value = dictionary[key] as? T ?? defaultValue
        return value as T
    }


// Can be curried inside a init?(json:NSDictionary) function 

        let stringAtKey:(String) -> String = { key in
            return unwrap(dictionary , key:key, defaultValue:"")
        }
        
        let numberAtKey:(String) -> NSNumber = { key in
            return unwrap(dictionary , key:key, defaultValue:NSNumber(int:0))
        }
        
        let boolAtKey:(String) -> Bool = { key in
            return unwrap(dictionary , key:key, defaultValue:false)
        }