Sort and combine elements to be unique - swift

Question

I have a bunch of tokens stored in combinedCoinsFromAllWalles and I'm sorting them by who contains the largest monetary value like this:
let sortedCoins = combinedCoinsFromAllWalles.sorted() { Double($0.token!.quote!) > Double($1.token!.quote!) }
The problem is that some tokens are repeated by name, for example, on that sorting I could have 2 tokens with the same name on $0.token!.name
What would be the most efficient way to also combine those similar tokens and add their value? Something like this:
token A (named BTC)
token B (named BTC)
token C (named ETH)
I want to sum token A and B quote ($0.token!.quote! + $0.token!.quote!) while filtering.
How do I do that in the most efficient way?

Answer 1

That first sort in your example is a waste since you have not combined all the different sources for similar coins first and the order may then change.
You should:
Aggregate coin values
Sort by desired order
One simple way to do this would be to create a dictionary, adding new coins or summing totals as you iterate through your data. Then convert the dictionary back to an array and sort how you would like.
Ex:
var dict: [String: Float] = []
for each in combinedCoinsFromAllWalles {
if dict.contains(each.token) {
dict[each.token] += each.quote
}else{
dict[each.token] = each.quote
}
}
let sortedCoinValueArray = dict.sorted(by: $0.1 < $1.1)
The resulting array is an array of key-value pairs, so you may iterate over it like this:
for (key, value) in sortedCoinValueArray {
print("${key}: ${value}"
}