Чтобы найти индекс строки в массиве в Swift, вы можете использовать несколько методов. Вот несколько примеров:

Метод 1: использование метода firstIndex(of:)

let array = ["apple", "banana", "orange"]
let searchString = "banana"
if let index = array.firstIndex(of: searchString) {
    print("Index of \(searchString): \(index)")
} else {
    print("\(searchString) not found in the array")
}

Метод 2: использование метода index(where:)

let array = ["apple", "banana", "orange"]
let searchString = "banana"
if let index = array.index(where: { $0 == searchString }) {
    print("Index of \(searchString): \(index)")
} else {
    print("\(searchString) not found in the array")
}

Метод 3. Использование цикла for

let array = ["apple", "banana", "orange"]
let searchString = "banana"
var index = -1
for (currentIndex, element) in array.enumerated() {
    if element == searchString {
        index = currentIndex
        break
    }
}
if index != -1 {
    print("Index of \(searchString): \(index)")
} else {
    print("\(searchString) not found in the array")
}