How can I perform an Array Slice in Swift?

Question

var mentions = ["@alex", "@jason", "@jessica", "@john"] 

I want to limit my array to 3 items, so I want to splice it:

var slice = [String]() if mentions.count > 3 {     slice = mentions[0...3] //alex, jason, jessica } else {     slice = mentions } 

However, I'm getting:

Ambiguous subscript with base type '[String]' and index type 'Range'

Apple Swift version 2.2 (swiftlang-703.0.18.8 clang-703.0.31) Target: x86_64-apple-macosx10.9

Answer 1

The problem is that mentions[0...3] returns an ArraySlice<String>, not an Array<String>. Therefore you could first use the Array(_:) initialiser in order to convert the slice into an array:

let first3Elements : [String] // An Array of up to the first 3 elements. if mentions.count >= 3 {     first3Elements = Array(mentions[0 ..< 3]) } else {     first3Elements = mentions } 

Or if you want to use an ArraySlice (they are useful for intermediate computations, as they present a 'view' onto the original array, but are not designed for long term storage), you could subscript mentions with the full range of indices in your else:

let slice : ArraySlice<String> // An ArraySlice of up to the first 3 elements if mentions.count >= 3 {     slice = mentions[0 ..< 3] } else {     slice = mentions[mentions.indices] // in Swift 4: slice = mentions[...] } 

Although the simplest solution by far would be just to use the prefix(_:) method, which will return an ArraySlice of the first n elements, or a slice of the entire array if n exceeds the array count:

let slice = mentions.prefix(3) // ArraySlice of up to the first 3 elements 

Answer 2

We can do like this,

let arr = [10,20,30,40,50] let slicedArray = arr[1...3] 

if you want to convert sliced array to normal array,

let arrayOfInts = Array(slicedArray)