Swift Array - Check If an Index Exists

Swift Array - Check if an index exists

An elegant way in Swift:

let isIndexValid = array.indices.contains(index)

How Can I Check My Array Index is Out of Range in Swift

It would be better to use an optional extension which returns nil if the element at the index doesn't exist.

Extension

extension Collection where Indices.Iterator.Element == Index {
    subscript (optional index: Index) -> Iterator.Element? {
        return indices.contains(index) ? self[index] : nil
    }
}

Usage:

mannschaft18teamid = results2.data.table[optional: 17]?.team_id ?? "not existing"

Check if array contains an index value in Swift

If you're dealing with array of integers and are only worried about the first two items, you can do something like:

let items: [Int] = [42, 27]
let firstItem  = items.first ?? 0
let secondItem = items.dropFirst().first ?? 0

Whether you really want to use the nil coalescing operator, ?? to make missing values evaluate to 0, or just leave them as optionals, is up to you.

Or you could do:

let firstItem  = array.count > 0 ? array[0] : 0
let secondItem = array.count > 1 ? array[1] : 0

How do I check if an array index is out of range SWIFT

Before indexing into the array, you need to check:

1. The intended index is not below 0
2. array's count is above the intended index

---

let intendedIndex: Int = 3

if (intendedIndex >= 0 && questions.count > intendedIndex) {
    // This line will not throw index out of range:
    let question3 = questions[intendedIndex]
}

SwiftUI: checking if next index exists in a ForEach

You need to iterate your collection indices and check if the index + 1 is less then the collection endIndex:

ForEach(item.currency.indices) {
    Text(verbatim: item.currency[$0])
        .font(Font.custom("Avenir", size: 18))
        .foregroundColor(Color("47B188"))
        .padding(.leading, 18)
    if $0 + 1 < item.currency.endIndex {
        Text("|")
    }
}

How to check if an element is in an array

Swift 2, 3, 4, 5:

let elements = [1, 2, 3, 4, 5]
if elements.contains(5) {
    print("yes")
}

contains() is a protocol extension method of SequenceType (for sequences of Equatable elements) and not a global method as in
earlier releases.

Remarks:

• This contains() method requires that the sequence elements
  adopt the Equatable protocol, compare e.g. Andrews's answer.
• If the sequence elements are instances of a NSObject subclass
  then you have to override isEqual:, see NSObject subclass in Swift: hash vs hashValue, isEqual vs ==.
• There is another – more general – contains() method which does not require the elements to be equatable and takes a predicate as an
  argument, see e.g. Shorthand to test if an object exists in an array for Swift?.

Swift older versions:

let elements = [1,2,3,4,5]
if contains(elements, 5) {
    println("yes")
}

ios how to check if object in array in particular index exist?

It is my understanding that you cannot have an index of an array unless you have and object there. What I would suggest is to set all indexes in the array to [NSNull null] and then in your if statement check to see if the object at that index is an NSNull object. if([[self.myArray objectAtIndex:index] isKindOfClass:[NSNull class]]) then if that returns true, have it replace the null object with your object

Check if index exists for Array of NSURL

You can find it through count

var data = [[String]]()

let data1 = ["test 1","test 2"]
data.append(data1)

let indexToFind = 1

if data[0].count > indexToFind {
    print("found")
    print("value \(data[0][indexToFind])")
}
else {
    print("not found")
}

---

If indexToFind = 2 then you will get

not found

If indexToFind = 1 then you will get

found

value test 2

---

FOR URL

You can count characters in url by absoluteString.characters.count

var data = [[NSURL?]]()

let data1 = [NSURL(string: ""),NSURL(string: ""),NSURL(string:"http://google.com")]
data.append(data1)

let indexToFind = 2

if data[0].count > indexToFind {
    print("found")
    print("value \(data[0][indexToFind]!)")

    if data[0][indexToFind]!.absoluteString.characters.count > 0 {
        print("this is an url")
    }
}
else {
    print("not found")
}

OUTPUT :

found

value http://google.com

this is an url

---

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