I'm trying to find the place of a value in a an array containing structures. My array looks like this
struct User {
var firstName: String?
var lastName: String?
}
var allThePeople = [User(firstName: "John", lastName: "Doe"), User(firstName: "Jane", lastName: "Doe"), User(firstName: "John", lastName: "Travolta")];
Is there a way to get the places for all "Doe"'s in the array? (in this case 0 and 1)
You can filter allThePeople with a condition to get all the people with the last name "Doe".
let allTheDoes = allThePeople.filter { $0.lastName == "Doe" }
You can enumerate the array and flat map it to an array of indices.
let allTheDoeIndexes = allThePeople.enumerated().flatMap { $0.element.lastName == "Doe" ? $0.offset : nil }
= allThePeople.enumerated().flatMap { $1.lastName == "Doe" ? $0 : nil }
{ $1.lastName == "Doe" ? $0 : nil } – perhaps a matter of taste.
flatmap is way more concise than my for loop answer (I upvoted you) - but it may be too terse for a novice - consider adding a bit of explanation?
allThePeople.enumerated().flatMap { $1.firstName == "John" && $1.lastName == "Doe" ? $0 : nil }If you want the actual indices, use something like
struct User {
var firstName: String?
var lastName: String?
}
var allThePeople = [User(firstName: "John", lastName: "Doe"), User(firstName: "Jane", lastName: "Doe"), User(firstName: "John", lastName: "Travolta")]
var indices = [Int]()
for i in 0 ..< allThePeople.count {
if allThePeople[i].lastName == "Doe" {
indices.append(i)
}
}
indices // [0,1]
otherwise use filter as @Callam suggested.