Creating a temporary file

Swift:
Creating a temporary file

How to:

Swift makes creating temporary files pretty easy, using the FileManager class. Here’s how you whip up a temp file and write some text into it:

import Foundation

// Create a temporary directory URL
let tempDirectoryURL = FileManager.default.temporaryDirectory

// Create a unique file name
let fileName = UUID().uuidString

// Construct the full file URL
let fileURL = tempDirectoryURL.appendingPathComponent(fileName)

// Sample text to write
let sampleText = "Hello, temporary world!"

do {
    // Write the text to the temporary file
    try sampleText.write(to: fileURL, atomically: true, encoding: .utf8)
    print("File created: \(fileURL)")
} catch {
    print("Failed to write to file: \(error)")
}

// Sample output:
// File created: file:///path/to/temp/directory/E0B4952E-5BEE-47E7-B5BB-DA5E6AF1EDC9

To read the file, just flip the script—here’s how:

do {
    // Read the text from the temporary file
    let savedText = try String(contentsOf: fileURL, encoding: .utf8)
    print("File contents: \(savedText)")
} catch {
    print("Failed to read file: \(error)")
}

// Sample output:
// File contents: Hello, temporary world!

Clean up after yourself by deleting the temp file:

do {
    // Delete the temporary file
    try FileManager.default.removeItem(at: fileURL)
    print("Temporary file deleted.")
} catch {
    print("Failed to delete file: \(error)")
}

// Sample output:
// Temporary file deleted.

Deep Dive

Before FileManager, folks managed files in more cumbersome ways. Remember C’s tmpfile()? Swift’s FileManager is a breath of fresh air in comparison: simple and modern.

Alternatives? Sure. You might use in-memory representations like Data or String, perfect for truly temporary data with limited size. Another route is to use a custom temp file manager for more control, but that’s typically overkill.

The nitty-gritty: FileManager uses the system’s temp directory, which is cleaned out occasionally but not after each program run. Keep that in mind when it comes to security or sensitive data—clean up manually if necessary.

Swift:Creating a temporary file

How to:

Deep Dive

See Also

Swift:
Creating a temporary file