Comparing strings in an array to another array using switch case - ios

Question

I am new here so please forgive me if I do not ask the right question. I am trying to create a function that will take array of strings ( medications) and then will tell if it belongs to certain categories by comparing it against other arrays. I am trying to achieve this with case switch method. But it is giving me error "can't form range upperBound
The code if have is :
//This is list of medications a patient may be on. This array will be generated by user input.
var medicationArray = ["metoprolol", "Dulera", "Atrovastatin", "Albuterol", "lasix", "Sprinolactone", "Lisnopril","Aspirin","Apixaban"]
//Function to compare medications above to arrays of different categories of medications.
func medDetails(medications : [String]) {
//Arrays of list of different types of mjedications
let betaBlockerList = ["metoprolol", "carvedilol", "propanolol"]
let anticoagulantList = ["warfarin", "Apixaban","rivroxaban"]
var otherMedicationList : String = ""
// For loop to loop thru different medications patient is on.
for medication in medications {
//switch function to take the medication name and then comparing it against different arrays.
switch medication {
//comparing medication against the range of of elements of first array.
case anticoagulantList[0]...anticoagulantList[anticoagulantList.count-1]:
print("Patinet is on \(medication) for anticoagultion")
//comparing medication against the range of of elements of second array.
case betaBlockerList[0]...betaBlockerList[betaBlockerList.count-1]:
print("Patient is on \(medication) for betablocker")
//list of medications that do not fit any of the above two categorias.
default:
otherMedicationList = medication + ", "
if medication == medications[medications.count - 1]{
print("Patients other medications inculde \(otherMedicationList) .")
}
}
}
}
medDetails(medications: medicationArray

Answer 1

let betaBlockerList = ["metoprolol", "carvedilol", "propanolol"]
Your switch case for "betaBlockerList" works fine. It is taking characters from "m" to "p" as parameters. Here these two values are in ascending order.
let anticoagulantList = ["warfarin", "Apixaban","rivroxaban"]
Your switch case for "anticoagulantList" is not working due to non ascending order of "(w)arfarin" and "(r)ivroxaban"
Switch cases here is not taking the whole strings as their parameters. Your betaBlockerList case is executing for all below values too
var medicationArray = ["metoprolol", "n", "o"]

Answer 2

I think a switch is not really a best practice here. A good approach would be to use a search function that searches or filters your array based on a given premise. But if you want to implement a more naive solution, simply do two for loops. One for the medicines and one for the other array that you are comparing against. Then add an if statement inside the loops, checking if the medicine is part of that list, if so, you have found your answer and you can break the loop at that point.

Answer 3

#Nirav already commented on the error, but the thing is that a switch might not be the best solution for your problem (what if you had 300 groups for example?)
So, here is a version that would require only a definition of the groups:
var medicationArray = ["metoprolol", "Dulera", "Atrovastatin", "Albuterol", "lasix", "Sprinolactone", "Lisnopril","Aspirin","Apixaban"]
func medDetails(medications: [String]) {
let input = Set(medications)
let betaBlockerList = Set(["metoprolol", "carvedilol", "propanolol"])
let anticoagulantList = Set(["warfarin", "Apixaban","rivroxaban"])
let groups = [
"betablocker": betaBlockerList,
"anticoagultion": anticoagulantList
]
// Get rid of any element from input that is present in groups
let unmatched = input.subtracting(groups.values.flatMap({$0}))
for medication in input {
for (groupName, groupValues) in groups {
if groupValues.contains(medication) {
print("Patient is on \(medication) for \(groupName)")
break
}
}
}
print("Patients other medications include: \(unmatched.joined(separator: ", "))")
}
Which when called like medDetails(medications: medicationArray) prints
Patient is on metoprolol for betablocker
Patient is on Apixaban for anticoagultion
Patients other medications include: Sprinolactone, Atrovastatin, Dulera, Albuterol, Aspirin, Lisnopril, lasix