How to get index of Class item in array with Swift 4?

Question

I have class as shown below:

struct Cur: Decodable {
    let id: String
    let name: String
    let symbol: String
    let switchVal:Bool
}

This class populates an array and the array is being displayed in UITableView. How to detect which switch button (switchVal) is toggled, therefore how to get "id" of the related element.

I am detecting when UISwitchButton is toggled inside a prototype cell like this:

@IBAction func switchBtn(_ sender: UISwitch) {
     if sender.isOn {

     }
}

Not related to your question but don't use implicitly unwrapped optionals in your properties — Leo Dabus
– Leo Dabus, Commented Oct 24, 2017 at 22:59
And isOn is a non optional Bool. Using == true is redundant. To check if not isOn just use if !sender.isOn — Leo Dabus
– Leo Dabus, Commented Oct 24, 2017 at 23:12

Leo Dabus · Accepted Answer · 2017-10-24 23:11:25Z

2

You can use index(where:) method to find the index of your array element as follow:

struct Cur: Decodable {
    let id: String
    let name: String
    let symbol: String
    let switchVal: Bool
}

let cur1 = Cur(id: "a", name: "john", symbol: "j", switchVal: false)
let cur2 = Cur(id: "b", name: "steve", symbol: "s", switchVal: true)
let cur3 = Cur(id: "c", name: "Carl", symbol: "c", switchVal: false)

let list = [cur1, cur2, cur3]

if let index = list.index(where: {$0.switchVal}) {
    print(list[index]) // Cur(id: "b", name: "steve", symbol: "s", switchVal: true)\n"
    print(list[index].id)  // "b\n"
}

edited Oct 24, 2017 at 23:11

answered Oct 24, 2017 at 23:04

Leo Dabus

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1 Comment

Vetuka Over a year ago

Hello, I am sure your code will work flawlessly and thank you for that. However, I am getting error "fatal error: unexpectedly found nil while unwrapping an Optional value". I am sure this has to do with my force-unwraps. Have to figure out those optionals. Thank you!

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