How to write [String] to text file in Swift?

Question

I create an array in swift like so:

var imagesArray = [String]()

and I add some base64 images to that array like so:

imagesArray.append(imageBase64String!)

Now I need to create a text.txt file and write the imagesArray into that file so I can send it to the server.

I tried this:

let fileName = "myFile.txt"
let url = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(fileName)

let data = Data(imagesArray)
do {
    try data.write(to: url, options: .atomic)
    print(url)
} catch {
    print(error)
}

But this produces this error:

No exact matches in call to initializer

which is infant of this code: let data = Data(imagesArray)

could someone please advice on this issue?

aheze · Accepted Answer · 2021-03-26 21:30:44Z

2

There's no built-in initializer for Data that takes in a [String]. imagesArray is a [String], so it doesn't work.

How do you want to save the array of Strings? If you want a new line between each String, you can try something like this (no need to use Data, instead, combine the array into 1 string):

let fileName = "myFile.txt"
let url = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(fileName)

let joinedImagesArray = imagesArray.joined(separator: "\n") /// separated by newline
do {
    try joinedImagesArray.write(toFile: url.path, atomically: true, encoding: .utf8)
    print(url)
} catch {
    print(error)
}

edited Mar 26, 2021 at 21:30

answered Mar 26, 2021 at 20:24

aheze

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4 Comments

drago Over a year ago

the code you've provided throws a few errors!

drago Over a year ago

This works with no error: try joinedStrings.write(toFile: outputURL.path, atomically: true, encoding: .utf8)

aheze Over a year ago

@rooz far glad you figured it out! I didn’t test my answer, should have.

Leo Dabus Over a year ago

iOS 10+ you can simply use FileManager.default.temporaryDirectory. Btw there is also a URL version of the write method. write(to: url, ...

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