How to parse JSON data with the same key and different data? - ios

Question

I have a little problem with parse JSON data.
There have a Web API，basic response data like this:
{
topic_name: "Kevin",
topic_type: 1,
extraData: {}
}
With the different topic_type value, the extraData maybe have different data structure, e.g the extraData object has different key-values.
In this case, how to create model classes and parse the JSON string to models?
Or does this API design reasonable? Is there a better API design to solve these cases?
update 1:
With the same topic_type, the extraData's structure is always same.
I have considered use subclasses, but it need a subclass for every topic_type.
update 2:
Here is some example of JSON data, different topic_type with different extraData.
when topic_type equal to 1,
{
topic_name: "Kevin",
topic_type: 1,
extraData: {
data_type1: value,
data_type2: value2
}
}
when topic_type equal to 2,
{
topic_name: "David",
topic_type: 2,
extraData: {
data_type3: value3
}
}
it not real data, I'm not deal with a 'topic' issue, just a example, the key is the extraData object has different type keys.

Answer 1

JSONModel might be exactly what you're looking for. Parses json and gives you models

Answer 2

try to define all types in a class:
{
topic_name: "Kevin",
topic_type: 1,
extraData: {
data_type1: value,
data_type2: value2,
data_type3: value3,
}
}
after Json parsing, take the data types u need based on topic type.
Ps. All data types need to be nullable