Swift3でのロギングどうしようかな、ライブラリを使うべきかなというところ「Swiftの自前ログクラス」を見つけ試したところ、例によってSwift3ではコンパイルが通らなかった部分がありましたので、Swift3対応版をば。

Usage

Logger.info(message: "init")
>> [INFO] => "init" 2017/01/31 11:11:11 init() MyViewController.swift:(37)

Logger.debug(message: "deinit")
>> [DEBUG] => "deinit" 2017/01/31 12:12:12 deinit() MyViewController.swift:(45)

Logger.swift

import Foundation

class Logger{
    class func debug(
        message: String,
        function: String = #function,
        file: String = #file,
        line: Int = #line) { Logger.write(loglevel: "[DEBUG]", message: message, function: function, file: file, line: line) };
    class func info(
        message: String,
        function: String = #function,
        file: String = #file,
        line: Int = #line) { Logger.write(loglevel: "[INFO]", message: message, function: function, file: file, line: line) };
    class func warning(
        message: String,
        function: String = #function,
        file: String = #file,
        line: Int = #line) { Logger.write(loglevel: "[WARNING]", message: message, function: function, file: file, line: line) };
    class func error(
        message: String,
        function: String = #function,
        file: String = #file,
        line: Int = #line) { Logger.write(loglevel: "[ERROR]", message: message, function: function, file: file, line: line) };
    class func write(
        loglevel: String,
        message: String,
        function: String,
        file: String,
        line: Int) {
        
        let now = NSDate() // 現在日時の取得
        let dateFormatter = DateFormatter()
        dateFormatter.locale = NSLocale(localeIdentifier: "ja_JP") as Locale!
        dateFormatter.timeStyle = .medium
        dateFormatter.dateStyle = .medium
        
        let nowdate = dateFormatter.string(from: now as Date)
        
        var filename = file
        if let match = filename.range(of: "[^/]*$", options: .regularExpression) {
            filename = filename.substring(with: match)
        }
    
        print("\(loglevel) => \"\(message)\" \(nowdate) \(function) \(filename):(\(line))")
    }
}

もっとリッチなロギングが欲しくなったらそのとき考えるということで。