Basic Logger - Swift 3 Version

Swift3BasicLogger.swift

/*
from console. `po NSHomeDirectory()`
from terminal cd to that path
cd into Documents
LogFile.txt should be there

To see content update live run tail -F LogFile.txt
*/

public class BasicLogger: NSObject {
    private static let queue = DispatchQueue(label: "com.vhart.basicLoggerQueue")
    private static let dateFormatter = DateFormatter()

    fileprivate static var filePath: String {
        let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory,
                                                        .userDomainMask,
                                                        true)
        let documentsDirectory = paths[0] as NSString
        return documentsDirectory.appendingPathComponent("LogFile.txt")
    }

    class func write(file: String = #file,
                     function: String = #function,
                     line: Int = #line,
                     message: String) {

        let fileName = (file as NSString).lastPathComponent
        write("\(fileName) \(function): \(line): -- \(message)")
    }

    // For Obj-C compatability
    //
    // Convert __FILE__ using [NSString stringWithFormat:@"%s", __FILE__
    // Same for __FUNCTION__
    //
    // [BasicLogger objcWriteFile: [NSString stringWithFormat:@"%s", __FILE__]
    //                   function: [NSString stringWithFormat:@"%s", __FUNCTION__]
    //                       line: __LINE__
    //                    message: @"Example message"];
    //
    @objc public class func objcWriteFile(file: String,
                             function: String,
                             line: Int,
                             message: String) {
        objc_sync_enter(self)
        defer { objc_sync_exit(self) }
        let fileName = (file as NSString).lastPathComponent
        write("\(fileName) \(function): \(line): -- \(message)")
    }


    fileprivate class func write(_ str: String) {
        queue.async {
            dateFormatter.dateFormat = "MM-dd-yyyy'| 'HH:mm:ss +SSS'|'"
            let dateNow = Date()
            let content = "\(dateFormatter.string(from: dateNow)): - \(str)\n"

            if let fileUpdater = try? FileHandle(forUpdating: URL(fileURLWithPath: filePath)) {
                fileUpdater.seekToEndOfFile()
                fileUpdater.write(content.data(using: .utf8)!)
                fileUpdater.closeFile()
            } else {
                do {
                    try content.write(toFile: filePath,
                                      atomically: true,
                                      encoding: .utf8)
                } catch let error as NSError {
                    print("Could not append to file: \(error.localizedDescription)")
                }
            }
        }
    }
}