how do i make sure users can't enter in duplicates? - arrays

Question

Spent all day on this one. I have an array of expenses that populates my tableview. Users can select a row from the tableview to edit the expense, which includes the name, the amount, the due date, etc.
I don't want users to be able to enter in a duplicate name. What I mean is, I want to check their input against the array to make sure the name doesn't already exist. This sounds simple to me, but for some reason I can't get it to work.
This is what I've tried:
CODE #1:
var duplicateCount = 0
for item in Expense.expensesArray.filter({ $0.ownerName == currentUserName }).filter({ $0.category == expense?.category }) {
if item.expenseName != expense?.expenseName {
print("no duplicates found in \(item.expenseName). moving on")
} else if item.expenseName == expense?.expenseName {
duplicateCount += 1
print("duplicate found in \(item.expenseName)")
}
}
CODE #2: (which is pretty similar to #1)
var duplicatesAmount: Int = 0
for expense in Expense.expensesArray.filter({ return $0.ownerName == currentUserName }).filter({ $0.category == expense?.category }) {
if expense.expenseName.lowercased() == expenseNameTextField.text?.lowercased() {
duplicatesAmount += 1
print("POTENTIAL DUPLICATE #\(duplicatesAmount): ",expense.expenseName)
}
}
// if there is more than one expense in the array with the same name, return true
if duplicatesAmount > 1 {
return true
} else {
return false
}
EDIT: The code runs whether there's a duplicate or not. It never sees the duplicate, even if I purposely put one in.
UPDATE: This worked.
if expense?.expenseName == expenseNameTextField.text {
updateExpenseInfo()
} else {
// iterate over the array and see if new name is found anywhere
let dupArray = Expense.expensesArray.filter({ $0.ownerName == currentUserName && $0.category == expense?.category && $0.expenseName == expenseNameTextField.text })
if dupArray.isEmpty {
updateExpenseInfo()
} else {
duplicateNameAlert()
}
}

Answer 1

You can do it like this:
struct Object {
let name: String
let amount: Int
init(name: String = "", amount: Int = 0) {
self.name = name
self.amount = amount
}
}
let a = Object(name: "Foo", amount: 10)
let b = Object(name: "Bar", amount: 20)
let array = [a, b]
func contains(value: String) -> Bool {
return array.filter({ $0.name == value }).isEmpty
}
print(contains(value: "Foo")) // true
print(contains(value: "Test")) // false
So you basically just add the contains function and return array.filter({ $0.name == value }).isEmpty. If it returns true then save otherwise don´t save. The value you pass it the entered value.