How to find index of list item in Swift?

Question

I am trying to find an item index by searching a list. Does anybody know how to do that?

I see there is list.StartIndex and <

Answer 1

Swift 2.1

var array = ["0","1","2","3"]

if let index = array.indexOf("1") {
   array.removeAtIndex(index)
}

print(array) // ["0","2","3"]

Swift 3

var array = ["0","1","2","3"]

if let index = array.index(of: "1") {
    array.remove(at: index)
}
array.remove(at: 1)

Answer 2

in Swift 4.2

.index(where:) was changed to .firstIndex(where:)

array.firstIndex(where: {$0 == "person1"})

Answer 3

You can also use the functional library Dollar to do an indexOf on an array as such http://www.dollarswift.org/#indexof-indexof

$.indexOf([1, 2, 3, 1, 2, 3], value: 2) 
=> 1

Answer 4

Swift 4. If your array contains elements of type [String: AnyObject]. So to find the index of element use the below code

var array = [[String: AnyObject]]()// Save your data in array
let objectAtZero = array[0] // get first object
let index = (self.array as NSArray).index(of: objectAtZero)

Or If you want to found index on the basis of key from Dictionary. Here array contains Objects of Model class and I am matching id property.

   let userId = 20
    if let index = array.index(where: { (dict) -> Bool in
           return dict.id == userId // Will found index of matched id
    }) {
    print("Index found")
    }
OR
      let storeId = Int(surveyCurrent.store_id) // Accessing model key value
      indexArrUpTo = self.arrEarnUpTo.index { Int($0.store_id) == storeId }! // Array contains models and finding specific one

Answer 5

Any of this solution works for me

This the solution i have for Swift 4 :

let monday = Day(name: "M")
let tuesday = Day(name: "T")
let friday = Day(name: "F")

let days = [monday, tuesday, friday]

let index = days.index(where: { 
            //important to test with === to be sure it's the same object reference
            $0 === tuesday
        })

Answer 6

Swift 4

For reference types:

extension Array where Array.Element: AnyObject {

    func index(ofElement element: Element) -> Int? {
        for (currentIndex, currentElement) in self.enumerated() {
            if currentElement === element {
                return currentIndex
            }
        }
        return nil
    }
}