Convert string into array without quotation marks in Swift 3

Question

My question:

This answer explains how to convert a String containing elements separated by spaces into an array.

let numbers = "1 2 3 4"
let numbersArray = numbers.components(separatedBy: " ")
print(numbersArray)
// output: ["1", "2", "3", "4"]
// but I want: [1, 2, 3, 4]

However, I'm trying to make an array without quotation marks, because I'm making an array of numbers, not strings.

My attempts:

I tried removing all quotation marks from numbersArray, but this didn't work as it's an array, not a string.

numbersArray.replacingOccurrences(of: "\"", with: "") // won't work

I tried something different: I tried adding each element in the array to a new array, hoping that new array wouldn't contain quotation marks. I got an error, though:

let numbers = "1 2 3 4" // string to be converted into array without quotes
let numbersArray = numbers.components(separatedBy: " ") // convert string into array with quotes
var newNumbersArray = [String]() // new blank array (which will be without quotes)
for i in numbersArray { // for each item in the array with quotes
  newNumbersArray += i // (hopefully) add the item in the new array without quotes
} 
print(newNumbersArray) // print the new array

This gives me an error:

Swift:: Error: cannot convert value of type '[String]' to expected argument type 'inout String'
  newNumbersArray += i

dfrib · Accepted Answer · 2017-08-01 09:45:43Z

2

You can apply a flatMap call on the [String] array resulting from the call to components(separatedBy:), applying the failable init(_:radix:) of Int in the body of the transform closure of the flatMap invokation:

let strNumbers = "1 2 3 4"
let numbersArray = strNumbers
    .components(separatedBy: " ")
    .flatMap { Int($0) }

print(numbersArray) // [1, 2, 3, 4]
print(type(of: numbersArray)) // Array<Int>

answered Aug 1, 2017 at 9:45

dfrib

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1 Comment

Oion Akif Over a year ago

Actually this answer is pretty sweet

Phyber · Accepted Answer · 2017-08-01 09:44:45Z

1

You can try this:

var newArray = [Int]()

for item in numbersArray{
    newArray.append(Int(item))
}

print(newArray)

answered Aug 1, 2017 at 9:44

Phyber

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5 Comments

Oion Akif Over a year ago

This worked! I did need to add an ! after Int(item) to unwrap it though

dfrib Over a year ago

@SkeletonBow I encourage you to try this approach but appending ! for say let numbersArray = "1 2 a 3 4". As a rule of thumb, if you're not entirely familiar with optionals, your should never use the forced unwrapping operator !.

Oion Akif Over a year ago

Okay, thank you. My app does crash. I just wanted to use ! here because it's much simpler and allows for more readable code, but I will keep your suggestion in mind and try a better approach (using if let or something)

dfrib Over a year ago

@SkeletonBow or possible the safe and quite readable flatMap approach shown in my answer below (which also allows you to let the newArray be immutable).

Oion Akif Over a year ago

I'm still a beginner, so I didn't quite understand your answer. I'll make a note to look at yours when I'm more experienced, though. In that way I'll actually be able to understand what I'm doing better :)

Jaydeep Vora · Accepted Answer · 2017-08-01 09:47:26Z

1

Swift 3.0

Try this.. Chaining method makes it easy.

let temp = "1 2 3 4 5 6"
var numbers: [Int] = []

temp.components(separatedBy: " ").forEach { numbers.append(Int($0)!) }

print(numbers) //[1, 2, 3, 4, 5, 6]

answered Aug 1, 2017 at 9:47

Jaydeep Vora

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1 Comment

Oion Akif Over a year ago

I would have selected this as the answer, but the current accepted answer is basically what I was trying to do, but corrected. This is also a very good answer, though.

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