Log provides a way to log stuff to the console and to file. It provides the method Log.print() which require minimal changes to your code because you probably already use Swift.print().
This creates a file log output in the default logs directory (path/to/application-support-dir/Logs) with a name containing the current month and year (e.g. log-2018-10.txt for October 2018).
guard let dirURL = Logging.defaultLogsDirectoryURL() else {
Swift.print("Logs directory not found")
return
}
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "y-MM"
let fileName = "log-\(dateFormatter.string(from: Date()))"
let fileURL = dirURL.appendingPathComponent(fileName).appendingPathExtension("txt")
let output = FileOutput(filePath: fileURL.path)
Logger.sharedInstance.addOutput(output)
Swift.print("Log file placed at \(fileURL.path)")You can then start logging using Log.print().
Log.print("Ups, something went wrong")The log file will look like this
2018-10-29 12:27:11.050 Ups, something went wrong
If a user reports an issue with your app, you can attach the log files to an email like this.
The following example uses the last 2 log files and attaches them to a mail compose sheet.
let mailController = MFMailComposeViewController()
if let urls = Logging.fileURLs { // returns the log files sorted by the creation date
let fileManager = FileManager()
for url in urls.prefix(2) {
guard let data = fileManager.contents(atPath: url.path) else {
continue
}
// Attach log as text file
mailController.addAttachmentData(data, mimeType: "text/plain", fileName: url.lastPathComponent)
}
}