Flatten array of array of dictionaries, taking only values - swift

Question

I have this array structure:
[
[
keyA: value1,
keyB: value2
],
[
keyA: value3,
keyB: value4
],
[
keyA: value5,
keyB: value6
]
]
And what I want to achieve is flattening the array into a single dictionary like:
[value1: value2, value3: value4]
Probably to achieve this is using merge twice?
I have tried with:
arrayToFlatten.reduce([:]) { $0.merging($1) { (current, _) in current } }
but I did not get the expected result:
[
[keyA: value1],
[keyB: value2]
]
This structure is sourced from a plist file:

Answer 1

If I understand this question correctly, I think this is what you're looking for
let source = [
[
"code": "DZ",
"name": "ALGERIA",
],
[
"code": "AS",
"name": "AMERICAN SAMOA",
],
[
"code": "AO",
"name": "ANGOLA",
],
]
let result = Dictionary(uniqueKeysWithValues: source.lazy.map { dict in
return (key: dict["code"]!, value: dict["name"]!)
})
print(result) // => ["AO": "ANGOLA", "AS": "AMERICAN SAMOA", "DZ": "ALGERIA"]
Dictionary merging wasn't the right tool for the job. It would take the dict, merge it with the second, which has the same keys. According to the closure you gave it, when two keys clash, it should take the old value and not the one that's attempting to be merged in. So merging the second dict had no effect. Similarly, the third didn't have any effect, either. You should read the documentation.
I hope today you've learned the importance of a minimal, reproducible example and a clear question. If you had just said "here's my source data, here's the expected output," then a question like this could have been answered in seconds.