SLF4Swift - Simple Log Facade for Swift

Simple Log Facade for Swift serves as a simple facade for logging frameworks allowing the end user to plug in the desired logging framework at deployment time in your framework

let myLogger = SLF4Swift.getLogger("loggerName")
myLogger.info("my info message")
myLogger.log(.Error, "my error message")

A Simple Log Facade

• make your framework project or any part of your codes no dependent to an heavy logging frameworks
• allow to log into your framework, avoiding the use of println() or NSLog(), and let the end user capture this logs

For framework owner

Getting Logger

Getting the default one

let myLogger = SLF4Swift.defaultLogger

Get logger or create if not exist

let myLogger = SLF4Swift.createLogger("loggerKey")

Or get it, here logger could be nil

if let myLogger = SLF4Swift.getLogger("loggerKey") {..}

In framework get a logger with a public key, then the end user can create a LogFactoryType and decide according to this key the logger to return

Printing

myLogger.log(.Error, "my error message") // basic method
// and some shortcut
myLogger.info("my info message")
myLogger.warn("my warn message")
...
// if message compute in a long period of time
if myLogger.isLoggable(.Verbose) {
    myLogger.log(.Verbose, createLongMessageClosure())
}
if myLogger.exec(.Verbose) { // or with closure
    myLogger.log(.Verbose, createLongMessageClosure())
}

There is macro functions for default logger

SLFLogInfo("info message")
SLFLog(.Verbose, "verbose message")
...

By declaring typealias Log = SLFLogLevel you can also use default logger like this

Log.Info.message("info message")
Log.Verbose.message("verbose message")
Log.Verbose.trace()// print file, function and line

For the end user

Installing a logger factory

By default is installed a NullLoggerFactory, which disable log

SLF4Swift.setSharedFactory(NullLoggerFactory.instance)

To enable log, set your LogFactoryType

SLF4Swift.setSharedFactory(MyCustomLoggerFactory())

or add DEBUG to “Other Swift Flags” into “Swift Compiler - Custom Flags” section this add by default a SLFLoggerFactory, which use by default println()

SLF4Swift.setSharedFactory(SLFLoggerFactory.sharedInstance)

Custom factories and loggers

You can your create your own LogFactoryType and/or LoggerType

• then return a logger according to the logger key used by one framework

class MyCustomLoggerFactory: ProxyLoggerFactory {

    func getLogger(name: LoggerKeyType) -> LoggerType? {
        if name == AFrameWorkKey {
            return NullLogger.instance // deactive log for specifc logger
        }
        else if name == AnOtherFrameWorkKey {
            var logger = super.getLogger(name)
            logger.level = .DEBUG // set a specific log level
            return logger
        }
        return super.getLogger(name)
    }

What you can use

Extend

• SingleLoggerFactory if your factory use only one logger
• ProxyLoggerFactory if your want to use an another factory and make some adaptations
• SLFLoggerFactory and override doCreateLogger, if you want to store logger into a Dictionnary by key

Some basic loggers are already implemented into implementation folder

Some backend factories are already implemented into backend folder (see setup)

SLF4Swift.setSharedFactory(CocoaLumberjackMacroLoggerFactory.instance)

Don’t hesitate to fork this repository and PR additionnal LogFactoryType for your logging framework

Setup

Backend

CocoaLumberjack pod 'SLF4Swift/CocoaLumberjack'

XCGLogger pod 'SLF4Swift/XCGLogger'

SpeedLog pod 'SLF4Swift/SpeedLog'

Make your own framework dependent

In podspec

s.dependency 'SLF4Swift'

For additional logger ie. simple implementation

Add pod 'SLF4Swift/Impl' to your Podfile

Using xcode project

1. Drag the.xcodeproj file to your project/workspace or open it to compile it
2. Add the framework to your project

Roadmap

• Add some LogFactoryType implementations for well known logging frameworks
• Replace String by Printable object or @autoclosure () -> Printable?
• Allow to use another key type for logger, Hashable?
• Logging methods with arguments to format into LoggerType?

Issues

• Protocol or protocol implentations do not allow to give default value for functions parameters, caller context cannot be passed to log message (__FILE__, __LINE__, __FUNCTION__). If there is a way, I am interested to learn it

Licence

The MIT License (MIT)

Copyright (c) 2015 Eric Marchand (phimage)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Logo

By kodlian, inspired by apple swift logo

Why a logo?

I like to see an image for each of my project when I browse them with SourceTree