Get key and indices of selected elements Swift

Question

I have one dictionary that contains an Array of Dictionaries.

\"other\":(
    {
         \"grocery_section\" = other,
         name = test
    },
    {
                  


        

Answer 1

You can make use of flatMap and compactMap:

let matches = list.flatMap { key, value in
    // go through all elements in the array and convert the matching dictionaries in (key, index) pairs
    value.enumerated().compactMap { index, dict in
        dict["name"] == "test" ? (key, index) : nil
    }
}
print(matches)

Sample output:

[("other", 0), ("c0f5d6c5-4366-d310c0c9942c", 1)]

If you want to avoid repeated pairs for the same key, you can use map instead of compactMap:

let matches = list.map { key, value in
    (key, value.enumerated().compactMap { index, dict in
        dict["name"] == "test" ? index : nil
    })
}

Sample output:

[("other", [0]), ("c0f5d6c5-4366-d310c0c9942c", [1])]

The inner compactMap will build an array made of on only the items that have the name matching, while the outer flatMap will flatten an otherwise bi-dimensional array.

Answer 2

Enumerate the outer dictionary and get the indices with filter

var filteredDict = [String:[Int]]()
for (key, value) in dict {
    let indices = value.indices.filter{ value[$0]["name"] == "test" }
    if !indices.isEmpty { filteredDict[key] = indices }
}

The result is a [String:[Int]] dictionary, the keys are the dictionary keys, the values are the indices.
With the given data the result is ["c0f5d6c5-4366-d310c0c9942c": [1], "other": [0]]

If you want to update an item you have to specify the entire path due to value semantics

list[key]![index]["propertyName"] = value