11.4. 'Must Do's While Decoding JSON adopting Codable

Let's look into the example JSON response for the details endpoint again:

{
    "email": "[email protected]",
    "name": "Alice Smith",
    "phone": 6781234567
}

And the data model for the above JSON that adopts the Codable protocol is:

struct Contact: Codable{
    var name:String
    var email:String
    var phone:Int
}

So let's compare the two and think about what are the things we need to handle to parse data carefully from JSON response by adopting Codable:

• The names of the keys (e.g., "email") must match the names of the variables in the Codable struct (e.g., name).

• The types of the values in the response JSON must match the types of the variables in the Codable struct. For example, "phone": 6781234567 means the value for the key "phone" has a value of integer data type. So we must set the type of the variable phone in struct Contact to Int.

• You do not have to define variables for all the keys in JSON. You can selectively write variables to parse the needed data from a big JSON object.

So, the name and the data type of the variables in a Codable must match the name of the keys and the type of the values in JSON. Otherwise, JSON decoding will not work.