Unified Logging Wrapper

OSLog+Extensions.swift

import Foundation
@_exported import os.log

public extension OSLog {

    convenience init(_ bundle: Bundle = .main, category: String? = nil) {
        self.init(subsystem: bundle.bundleIdentifier ?? "default", category: category ?? "default")
    }

    convenience init(_ aClass: AnyClass, category: String? = nil) {
        self.init(Bundle(for: aClass), category: category ?? String(describing: aClass))
    }

    @inlinable func log(_ message: StaticString, _ args: CVarArg...) {
        log(message, type: .default, args)
    }

    @inlinable func info(_ message: StaticString, _ args: CVarArg...) {
        log(message, type: .info, args)
    }

    @inlinable func debug(_ message: StaticString, _ args: CVarArg...) {
        log(message, type: .debug, args)
    }

    @inlinable func error(_ message: StaticString, _ args: CVarArg...) {
        log(message, type: .error, args)
    }

    @inlinable func fault(_ message: StaticString, _ args: CVarArg...) {
        log(message, type: .fault, args)
    }

    func print(_ value: @autoclosure () -> Any) {
        guard isEnabled(type: .debug) else { return }
        os_log("%{public}@", log: self, type: .debug, String(describing: value()))
    }

    func dump(_ value: @autoclosure () -> Any) {
        guard isEnabled(type: .debug) else { return }
        var string = String()
        Swift.dump(value(), to: &string)
        os_log("%{public}@", log: self, type: .debug, string)
    }

    func trace(file: StaticString = #file, function: StaticString = #function, line: UInt = #line) {
        guard isEnabled(type: .debug) else { return }
        let file = URL(fileURLWithPath: String(describing: file)).deletingPathExtension().lastPathComponent
        var function = String(describing: function)
        function.removeSubrange(function.firstIndex(of: "(")!...function.lastIndex(of: ")")!)
        os_log("%{public}@.%{public}@():%ld", log: self, type: .debug, file, function, line)
    }

    @usableFromInline internal func log(_ message: StaticString, type: OSLogType, _ a: [CVarArg]) {
        // The Swift overlay of os_log prevents from accepting an unbounded number of args
        // http://www.openradar.me/33203955
        assert(a.count <= 5)
        switch a.count {
        case 5: os_log(message, log: self, type: type, a[0], a[1], a[2], a[3], a[4])
        case 4: os_log(message, log: self, type: type, a[0], a[1], a[2], a[3])
        case 3: os_log(message, log: self, type: type, a[0], a[1], a[2])
        case 2: os_log(message, log: self, type: type, a[0], a[1])
        case 1: os_log(message, log: self, type: type, a[0])
        default: os_log(message, log: self, type: type)
        }
    }
}

SampleViewController.swift

import UIKit

final class SampleViewController: UIViewController {

    // initialize with bundle identifier of the current class and optional category
    private let log = OSLog(SampleViewController.self, category: "UI")

    override func viewDidLoad() {
        super.viewDidLoad()

        // log messages using different levels
        log.log("default")
        log.info("info")
        log.debug("debug")
        log.error("error")
        log.fault("fault")

        // trace source location
        log.trace()

        // print object description
        log.print(view)

        // dump any object
        log.dump(view)
    }
}

https://www.bignerdranch.com/blog/migrating-to-unified-logging-swift-edition/
https://github.com/jaredsinclair/etcetera/blob/master/OSLog.swift