Removing Duplicates From Array of Custom Objects Swift

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Here is an Array extension to return the unique list of objects based on a given key:

extension Array {
    func unique<T:Hashable>(map: ((Element) -> (T)))  -> [Element] {
        var set = Set<T>() //the unique list kept in a Set for fast retrieval
        var arrayOrdered = [Element]() //keeping the unique list of elements but ordered
        for value in self {
            if !set.contains(map(value)) {
                set.insert(map(value))
                arrayOrdered.append(value)
            }
        }

        return arrayOrdered
    }
}

for your example do:

let uniqueMessages = messages.unique{$0.id ?? ""}

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