Get Index of Array containing Structs by searching for Struct Value using Swift 3.0

Question

I have a struct for holding data;

struct MyStruct {
  var age: Int
  var name: String
}

I make an array of this and fill it with data;

var myArray = [MyStruct]()
myArray[0] = MyStruct(age: 26, name: "John")
myArray[1] = MyStruct(age: 35, name: "Smith")

How can I find the index of the element in myArray that contains the name "Smith"?

Edit: Here's more context about where I need to find the location using the new code from Losiowaty;

func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
  let selection = tableView.cellForRow(at: indexPath)?.textLabel
  let name = selection!.text!
  let location = myArray.index(where: { $0.name == name})

  //additional code to comply with the function and return, unneeded for this context
}

1) Class/struct names should start with uppercase letters. 2) Why do you initialize age and name in your myStruct to useless values? 3) Why is myArray initialized with an empty myStruct? — rmaddy
– rmaddy, Commented Dec 14, 2016 at 22:13
1) Updated, my bad. 2) I'm not sure what you mean, the struct is just defining the data that's going to be stored, so when I add data later (the hard coded data is just an example, it will be based on user input in the final product). 3) I was defining the array as an array of myStruct() so data can be added later. I'll be using myArray.append based on user input later. — kingfoot
– kingfoot, Commented Dec 14, 2016 at 22:18
2) I'm referring to the unneeded = Int() and = String() on the two properties. 3) You want [MyStruct], not [MyStruct()]. The first declares an empty array that will contain instances of MyStruct. The seconds declares an array containing one instance of MyStruct. — rmaddy
– rmaddy, Commented Dec 14, 2016 at 22:25
Looks good now. Does the answer by Losiowaty work now after making those changes? — rmaddy
– rmaddy, Commented Dec 14, 2016 at 22:35

Losiowaty · Accepted Answer · 2016-12-14 22:53:58Z

17

You can use index(where:) method. A quick example :

let index = myArray.index(where: { $0.name == "Smith" })

In a case when there would be no such element, the method will return nil.

With more context from edits, the best (i.e. safest) way would be something like this :

if let name = selection?.name {
    if let location = myArray.index(where: { $0.name == name }) {
        // you know that location is not nil here
    }
}

Source - https://developer.apple.com/reference/swift/array/1688966-index

edited Dec 14, 2016 at 22:53

answered Dec 14, 2016 at 22:17

Losiowaty

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9 Comments

kingfoot Over a year ago

I gave it a go and I'm getting an error: Ambiguous reference to member '=='

Losiowaty Over a year ago

Strange, since this would be basic string comparison. Are you sure you didn't do $0 == "Smith"?

kingfoot Over a year ago

I left out some nuance to my actual code when I converted it to generic code. When I'm doing the find, I'm passing the name to be searched for as a stored variable let name = selection!.text.

Losiowaty Over a year ago

Ah, is this name an optional by chance? If so you simply need to unwrap it.

kingfoot Over a year ago

name is unwrapped when it's created. Please see my up updated edit! Thank you for the help so far.

|

SafeFastExpressive · Accepted Answer · 2019-06-29 00:48:35Z

5

For Swift 4: index(where:) has been deprecated, so now use firstIndex:

let index = firstIndex(where: { $0.name == "Smith" })

answered Jun 29, 2019 at 0:48

SafeFastExpressive

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Umar · Accepted Answer · 2019-09-04 12:00:50Z

0

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath:     IndexPath) {
    let MyStruct = myArray[indexPath.row]
    cell.yourLable?.text = MyStruct.name
       }

answered Sep 4, 2019 at 12:00

Umar

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