I am using SwiftyBeaver in TableFlip and my latest project. Doing some robust console and file logging is important, and this library seems to work just fine for my needs.

Except for error reporting. I do not want to attach the whole debug log when folks may report a simple problem. So I figured: maybe it’ll help to have the last 5 or 10 log messages attached upon a first error encounter.

So I wrote a SwiftyBeaver “in memory” destination that is set up next to a file and a console destination:

class InMemoryDestination: BaseDestination {

    var maxHistory = 5
    fileprivate(set) var messages: [String] = []

    override func send(_ level: SwiftyBeaver.Level, msg: String, thread: String, file: String, function: String, line: Int) -> String? {

        let formattedString = super.send(level, msg: msg, thread: thread, file: file, function: function, line: line) ?? "\(msg) (formatting error!)"

        messages = Array(messages
            .appending(formattedString)
            .suffix(maxHistory))

        return formattedString
    }
}

As a means to access these messages, I use a free function-like global closure:

let error = ...
let logMessages = lastLogMessages().joined(separator: "\n")
reportError(error: error, additionalInfo: logMessages)

Here, lastLogMessages is a closure so it can be swapped during runtime:

fileprivate(set) var lastLogMessages: () -> [String] = { return [] }

This then comes in handy when I set up my SwiftyBeaver logger:

let console = ...
let file = ...
let inMemory: InMemoryDestination = {
    let inMemory = InMemoryDestination()
    inMemory.maxHistory = 10
    inMemory.format = "$DHH:mm:ss: $M"
    inMemory.asynchronously = false

    // Here create a closure that points inside the InMemoryDestination:
    lastLogMessages = { return inMemory.messages }

    return inMemory
}()

SwiftyBeaver.addDestination(console)
SwiftyBeaver.addDestination(file)
SwiftyBeaver.addDestination(inMemory)

And that’s it! I get a buffer of 10 log messages and read access to said buffer when I prepare error report emails.

One step closer to releasing a version into the wild.