objective-c - I have defined a data model of dict type, so how do I find its sum?

Question

Prompt this error

Answer 1

Your mistake is that you called a count method. According to the name, it takes the quantity, but your question asked about summation. I don’t know what you want to do specifically. However, since ProductCategoryDataModel is customized by you, if its parent class does not have a count or sum method, you need to implement the corresponding method yourself before you can call it.

Answer 2

If you are counting the number of dictionaries,
somedict.allKeys.count
or
somedict.allValues.count

Answer 3

What class does

model inherit from?
In addition, you can implement the -count; method by yourself