Log4s

1. Feature List

Feature	Category	Status
Following Swift API Design guideline	Syntax	--
Javascript-like fluent interface	Syntax	--
Multiple expandable destinations (a.k.a Appenders)	Appender	DONE
Asynchronous logging support for Appenders	Appender	DONE
Appender for local persistent storage	Appender	UNDERGOING
Appender for other destinations	Appender	Coming
Built-in cascadable Layout components	Layout	DONE
Asynchronous support for Layout	Layout	DONE
Multiple tags support	Tags	DONE
Appender level tag filters	Tags	DONE
Directly log the type Any and Error	Misc	DONE
MaxSeverity for both Logger and Appender levels	Misc	DONE
Custom severity levels	Misc	DONE
Message masking	Misc	Coming
Compatible with Cocoapod and Carthage	Misc	Coming

2. Quick Usage

2.1 Setup

Universial Build

• Download Log4s.framework latest release from HERE
• Select your Target, then select the tab General, click + in the section of Embeded Binaries, then import Log4s.framework to your project, as shown in following snapshot.
• The universial build can be used for all arm and x64 architectures, which means you can use it for iOS device and iOS simulator. The support of OSX apps is undergoing.


2.2 Basic Usage

Start using the most basic function without any configuration or any unecessary parameters.

import Log4s	// Put this line in the header of the files


Logger.log("A Logging Message") // Most basic form
Logger.log("A debug message", severity:.debug) // With severity mentioned

//Below are some shortcuts for varies of built-in severities, with cascading expression

Logger
   .verbose("This is a VERBOSE message")
   .debug("This is a DEBUG message")
   .info("This is an INFO message")
   .warn("This is a WARN message")
   .error("This is an ERROR message")
   .fatal("This is a FATAL message") 

3 Layouts

3.1 Quick Examples

To build the layout of logging messages. Here is a quick example:

Logger.layout = [
   Layout.time(),	// the time when logging is called
   "{MyApp}",		// a pure string
   Layout.severity(),	// severity
   Layout.brackets().embed(			// a pair of brackets with embeded content
  		Layout.tags()			// the tags of the event, nested inside the brackets. See Chapter 4 for "Tags"  
   ),
   Layout.message()
   ]
   
Logger.error("Failed to find profile",tags:["LoginScene","Network"])

The ouput is

17/01/05 14:05:48 {MyApp} ERROR [LoginScene|Network] Failed to find profile

With more configurations in the above example, it can be:

Logger.layout = Layout.chain([
   Layout.time("HH:mm:ss"),	// assign the timestamp format
   "{MyApp}",
   Layout.severity(),
   Layout.brackets("<").embed([			// assign the brackets' type and embed another chain
   		"TAGS: ",
  		Layout.tags(dividedBy:",").uppercased()	// assign the delimiter of tags and use the uppercase
  		]
   ),
   Layout.message()
   ],dividedBy: "\t")	// insert "\t" between every two layout components
   
Logger.error("Failed to find profile",tags:["LoginScene","Network"])

The ouput comes to be

14:05:48	{MyApp}	ERROR	<TAGS: LoginScene|Network>	Failed to find profile

3.2 Layout Components

Name	Description	Example
TBD	Find the usage of layout components in SampleLogging.swift in SampleSwiftIOS project

3.3 Custom Layout

Override the function func present(_ event: Event) -> String to create customized Layout,

class MyLayout: Layout{
	override func present(_ event: Event) -> String {
		return "MyPrefix => [\(String(describing: event.sev))] \(event.message)"
	}
}

Logger.layout = MyLayout()
Logger.error("This is an error message presented by 'MyLayout'")

The output

MyPrefix => [ERROR] This is an error message presented by 'MyLayout'

Another quick way to implement custom layout is to use closure

Logger.use(layout: Layout(){ (event) -> String in
        return "'MyLayout' [\(String(describing: event.sev))] \(event.message)"
    })
Logger.error("The format of this message is defined by a closure")

The output

'MyLayout' [ERROR] The format of this message is defined by a closure

3.4 Asynchronous Layout

4. Tags and Filters

4.1 Multiple tags

4.2

5. Appenders

5.1

6.

Version