happycodelucky / SwiftAbstractLogger

Abstract, context-free logger for Swift packages. Permitting packages to implement logging without relying on a particular logging package, but leaving this to the consumer application.

SwiftAbstactLogger

Abstract, context-free logger for Swift packages. Permitting packages to implement logging without relying on a particular logging package, but leaving this to the consumer application.

Package Management

Installation

Using Swift Package Manager

SwiftAbstractLogger is available through Swift Package Manager. To install it, simply add the following line to your Package.swift dependencies:

.Package(url: "https://github.com/pryomoax/SwiftAbstractLogger.git", majorVersion: 0, minor: 3)

Using Carthage

SwiftAbstractLogger is available through Carthage. To install it, simply add the following line to your Cartfile:

# SwiftAbstractLogger
github "pryomoax/SwiftAbstractLogger.git" ~> 0.3

Using CocoaPods

SwiftAbstractLogger is currently not supported by CocoaPods (coming soon)

Usage

Any package using the SwiftAbstractLogger package will not log anything unless an application attached a logger. More than one logger can be attached to Logger if there is a need to support multiple loggers, say one to the console and another to the persisted resource.

Logging

Attaching Loggers

SwiftAbstractLogger contains a single default logger BasicConsoleLogger that can be attached.

Logger.attach(BasicConsoleLogger.logger)

Additional contirbution loggers can be attached in the same way

Logger.attach(MyLogger.logger)

Logging

Once a logger is attached, logging is as simple as using the convience logging function log.

log("Hello World")

Outputs the following log statement

Hello World

Logging other levels can be achieved by using the logging level convenice function logCritical|Error|Warning|Info|Verbose|Debug()

// Log debug statement
logDebug("Hello Debug World")

By default nothing will be logged with any logger attached because the default logging level is set to .info and logDebug() logs at the .debug level below the Logger.defaultLevel threshold.

// Set debug log level
Logger.defaultLevel = .debug

// Log debug statement
logDebug("Hello Debug World")

Outputs the following log statement

🐞 Hello Debug World

Category Logging

Changing the global logging level for all logs isn't desirable. With SwiftAbstractLogger being used by potentially multiple packages, changing the levels would output too many logs.

Category logging allows packages to scope logs and level to the package. Adding a category parameter to log or any level specialization, like logDebug. Scoping with categories permit log levels for that category to be configured independently.

// Set warning log level
Logger.defaultLevel = .warning

// Configure "MyCategory" to log at level Debug, below the global default level
Logger.configureLevel(category: "MyCategory", level: .debug)

logDebug("Global debug logging")
logDebug(category: "MyCategory", "MyCategory debug logging")

Outputs only the following logs

🐞 MyCategory debug logging

Custom Loggers

Implementing additional loggers is as simple as extending LoggerDelegate. BasicConsoleLogger is an example of this, but can be implemented by many other loggers.

There is only one function to implement to support a custom logger log(level:category:message:). All other management is handled by the top level Logger class

public protocol LoggerDelegate {
	func log(level: Logger.LogLevel, category: String?, message: String)
}

All logging will be dispatched to the main dispatch queue. Any logger wanting to dispatch to another queue should be taken care of by the LoggerDelegate implementation.

Package Information

Requirements

• Xcode 8
• iOS 10.0+
• tvOS 10.0+
• watchOS 3.0+
• macOS 10.12+

Author

Paul Bates, [e-mail]

License

AbstractLogger is available under the MIT license. See the LICENSE file for more info.