How to Get key value pair tuple array in swift?

Question

I have pairs tuple array pickerDataVisitLocation.just I want to know how to return key value pair location from my array using uniqId ex 204

var pickerDataVisitLocation:[(uniqId:Int,location:String)] = [(203,"Home"),(204,"Hospital"),(205,"Other")]
var selectedIndex = pickerDataVisitLocation[1].uniqId
pickerDataVisitLocation[selectedIndex].location //<--fatal error: Index out of range

Troll

So selectedIndex is 204, as that's the uniqId of item 1 in your array. Then you try to get pickerDataVisitLocation[204], but it only has 3 items. What's the problem? What do you expect it to do? – Alleris

Is a tuple even needed? I would just do a dictionary of [Int:String] – Cincinnati

what I want is to get pair value location"Hospital" that have uniqId is 204 – Troll

selectedIndex will be the one which you have given i.e 203,204,205 according to this code, and your array only has 3 elements – Allonym

Answer 1

Make use of Sequence's first(where:) method

You could make use of Sequence's first(where:) to access the first tuple element of the array that meets a boolean requirement based on the first member of the tuple elements (uniqId). For the resulting tuple element, simply access the second member of the tuple (location).

var pickerDataVisitLocation: [(uniqId: Int, location: String)] = 
    [(203, "Home"), (204, "Hospital"), (205, "Other")]

// say for a given uniqId 204
let givenId = 204
let location = pickerDataVisitLocation
               .first{ $0.uniqId == givenId }?.location ?? ""
print(location) // Hospital

---

If no tuple element can be found for a given id, the method above will result in a resulting string that is empty (due to the nil coalescing operator). As an alternative, you could use an optional binding clause to proceed only for a non-nil return from .first:

var pickerDataVisitLocation: [(uniqId:Int,location:String)] = 
    [(203,"Home"),(204,"Hospital"),(205,"Other")]

// say for a given uniqId 204
let givenId = 204
if let location = pickerDataVisitLocation
                  .first(where: { $0.uniqId == givenId })?.location {
    print(location) // Hospital
}

---

Possibly an alternative: consider using a dictionary

Finally, since the first member of you tuple elements, uniqId, hints at unique members, and its type Int being Hashable, you might want to consider making use of a dictionary rather than an array of tuples. This will ease access of values associated with give unique Int id's, but you will loose the ordering of "elements" (key-value pairs) in the dictionary, as dictionaries are unordered collections.

var pickerDataVisitLocation = [203: "Home", 204: "Hospital", 205: "Other"]

// say for a given uniqId 204
let givenId = 204
if let location = pickerDataVisitLocation[givenId] {
    print(location) // Hospital
}

Ammonia

I wish I can do more UpVote – Troll

@Troll happy to help :) – Ammonia

Hey @NinjaDeveloper, its been some years since this. I'm new to swift, how can I access more values from the struct instead of just one "?.location", what if I want all of the values corresponding. – Lockup

Answer 2

According to the given code:
Try this

var pickerDataVisitLocation:[(uniqId:Int,location:String)] = [(203,"Home"),(204,"Hospital"),(205,"Other")]
let selectedIndex = pickerDataVisitLocation[1].uniqId
var location = ""

for item in pickerDataVisitLocation {
    if item.uniqId == selectedIndex {
        location = item.location
    }
}

print(location) //Will print Hospital here

Allonym

Answer 3

You could try something like below.

extension Array {
    func tupleWithId(id: Int) -> (uniqId:Int,location:String)? {
        let filteredElements = self.filter { (tuple) -> Bool in
            if let tuple = tuple as? (uniqId:Int,location:String) {
                return tuple.uniqId == id
            }
            return false
        }

        if filteredElements.count > 0 {
            let element = filteredElements[0] as! (uniqId:Int,location:String)
            return element
        }
        return nil
    }
}
var pickerDataVisitLocation:[(uniqId:Int,location:String)] = [(203,"Home"),(204,"Hospital"),(205,"Other")]
var selectedIndex = pickerDataVisitLocation[1].uniqId
pickerDataVisitLocation.tupleWithId(id: selectedIndex)?.location

Swab