How to save a string to a file on disk with write(to:)
Swift version: 5.4
All strings have a write(to:) method that lets you save the contents of the string to disk. You need to provide a filename to write to, plus two more parameters: whether the write should be atomic, and what string encoding to use. The second parameter should nearly always be true because it avoids concurrency problems. The third parameter should nearly always be String.Encoding.utf8, which is pretty much the standard for reading and writing text.
Be warned: writing a string to disk can throw an exception, so you need to catch any errors and warn the user.
Here's the code:
let str = "Super long string here"
let filename = getDocumentsDirectory().appendingPathComponent("output.txt")
do {
try str.write(to: filename, atomically: true, encoding: String.Encoding.utf8)
} catch {
// failed to write file – bad permissions, bad filename, missing permissions, or more likely it can't be converted to the encoding
}That code uses a helper function called getDocumentsDirectory(), which finds the path to where you can save your app's files. Here it is:
func getDocumentsDirectory() -> URL {
let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
return paths[0]
}
SPONSORED From August 2nd to 8th you can join a FREE crash course for mid/senior iOS devs who want to achieve an expert level of technical and practical skills – it’s the fast track to being a complete senior developer!
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS 2.0
Similar solutions…
- How to save a UIImage to a file using jpegData() and pngData()
- How to load a string from a file in your bundle
- How to read your app’s version from your Info.plist file
- How to find the path to a file in your bundle
- How to write a closure that returns a value
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
