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SOLVED: Accessing an item in an array of struct instances

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@vtabmow  

I have an array of struct instances similar to something below, and I want to modify one of the entries. Assuming that I won't know before hand what the index of the item is in the array, how would I do that?

I'm assuming I would have to remove the item from the array and append it again, but I would also need to determine its index, unless there is a better method.

For example, Jane gets married and wants to have her last name changed to Thompson, what's a good way to do that if I don't know the index of the item ahead of time. 

struct Employee {
    let id: Int
    let firstName: String
    let lastName: String
}

var employees = [
Employee(id: 1, firstName: "Bob", lastName: "Jones"),
Employee(id: 2, firstName: "Tom", lastName: "Smith"),
Employee(id: 3, firstName: "Jane", lastName: "Wood"),
Employee(id: 4, firstName: "Karen", lastName: "Wim")
]

3      

@roosterboy  HWS+

You don't need to remove, change and append an item to accomplish this.

if let idx = employees.firstIndex(where: { $0.firstName == "Jane" }) {
    employees[idx].lastName = "Thompson"
}

Note: You will need to change your Employee struct since currently you can't change the lastName property anyway.

struct Employee {
    let id: Int
    var firstName: String //var, not let, if we want to be able to change
    var lastName: String //var, not let, if we want to be able to change
}

But if you want to do the remove, change, append dance...

Array has two methods that can combine to do what you want here, so let's wrap them up into a nifty extension.

extension Array {
    mutating func remove(where condition: (Element) -> Bool) -> Element? {
        guard let index = firstIndex(where: condition) else {
            return nil
        }

        return remove(at: index)
    }
}

We use firstIndex(where:) to find the item we want to remove, then remove and return it with remove(at:).

We can use this extension like so:

if var jane = employees.remove(where:{ $0.firstName == "Jane" }) {
    jane.lastName = "Thompson"
    employees.append(jane)
}

4      

@roosterboy  HWS+

Another option:

struct Employee {
    let id: Int
    let firstName: String //can make these let again
    let lastName: String //can make these let again
}

extension Employee {
    func getMarried(to newLastName: String) -> Employee {
        //create new Employee with same info except for lastName
        Employee(id: id, firstName: firstName, lastName: newLastName)
    }
}

if let jane = employees.remove(where:{ $0.firstName == "Jane" }) {
    employees.append(jane.getMarried(to: "Thompson"))
}

4      

@vtabmow  

I think I like the first option best.

if let idx = employees.firstIndex(where: { $0.firstName == "Jane" }) {
    employees[idx].lastName = "Thompson"
}

Though, I definitely will play around with the other stuff as well.

Thanks for the responses.

3      

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