removing duplicate airport codes string in an array in swift

Question

I have an array of strings which are airport codes something like this,

let list = [ "JFK-ATL-CDG-JFK",
             "HKG-MIA-NRT",
             "LAX-DFW-FRA-CDG-AMS-FRA-DFW",
             "PEK-SEA-MCO-YYZ-SEA",
             "MSP-DTW-BKK"]

What I want to do is return only the strings which has duplicate airport codes, so if a user visits the same city again then I would like that string to be returned in an array like this.

let updatedList = [ "JFK-ATL-CDG-JFK",
                    "LAX-DFW-FRA-CDG-AMS-FRA-DFW",
                    "PEK-SEA-MCO-YYZ-SEA"]

Second and third element in the array does not have duplicate codes so those are not returned in the new array, Notice that airport codes are separated by "-" does Swift provide a way to remove "-" and add them back? what is the easiest way to do this. Thanks.

Answer 1

you could try something simple like this, works for me:

let list = [ "JFK-ATL-CDG-JFK",
             "HKG-MIA-NRT",
             "LAX-DFW-FRA-CDG-AMS-FRA-DFW",
             "PEK-SEA-MCO-YYZ-SEA",
             "MSP-DTW-BKK"]

var updatedList: [String] = []
list.forEach { item in
    let test = item.split(separator: "-").map{String($0)}
    if test.count != Set(test).count {
        updatedList.append(item)
    }
}
print("\n---> updatedList: \(updatedList) \n")

Or, more succinctly:

let updatedList: [String] = list.compactMap{ item in
    let arrTest = item.split(separator: "-").map{String($0)}
    return arrTest.count != Set(arrTest).count ? item : nil
}