AWSDDLogger

Objective-C

@protocol AWSDDLogger <NSObject>

Swift

protocol AWSDDLogger : NSObjectProtocol

This protocol describes a basic logger behavior. Basically, it can log messages, store a logFormatter plus a bunch of optional behaviors. (i.e. flush, get its loggerQueue, get its name, …

  • The log message method

    Declaration

    Objective-C

    - (void)logMessage:(nonnull AWSDDLogMessage *)logMessage;

    Swift

    func log(message logMessage: AWSDDLogMessage)

    Parameters

    logMessage

    the message (model)

  • Formatters may optionally be added to any logger.

    If no formatter is set, the logger simply logs the message as it is given in logMessage, or it may use its own built in formatting style.

    Declaration

    Objective-C

    @property (nonatomic, strong, nullable) id<AWSDDLogFormatter> logFormatter;

    Swift

    var logFormatter: AWSDDLogFormatter? { get set }

  • Since logging is asynchronous, adding and removing loggers is also asynchronous. In other words, the loggers are added and removed at appropriate times with regards to log messages.

    • Loggers will not receive log messages that were executed prior to when they were added.
    • Loggers will not receive log messages that were executed after they were removed.

    These methods are executed in the logging thread/queue. This is the same thread/queue that will execute every logMessage: invocation. Loggers may use these methods for thread synchronization or other setup/teardown tasks.

    Declaration

    Objective-C

    - (void)didAddLogger;

    Swift

    optional func didAdd()

  • Since logging is asynchronous, adding and removing loggers is also asynchronous. In other words, the loggers are added and removed at appropriate times with regards to log messages.

    • Loggers will not receive log messages that were executed prior to when they were added.
    • Loggers will not receive log messages that were executed after they were removed.

    These methods are executed in the logging thread/queue given in parameter. This is the same thread/queue that will execute every logMessage: invocation. Loggers may use the queue parameter to set specific values on the queue with dispatch_set_specific() function.

    Declaration

    Objective-C

    - (void)didAddLoggerInQueue:(nonnull dispatch_queue_t)queue;

    Swift

    optional func didAdd(in queue: dispatch_queue_t)

  • See the above description for didAddLogger

    Declaration

    Objective-C

    - (void)willRemoveLogger;

    Swift

    optional func willRemove()

  • Some loggers may buffer IO for optimization purposes. For example, a database logger may only save occasionally as the disk IO is slow. In such loggers, this method should be implemented to flush any pending IO.

    This allows invocations of AWSDDLog’s flushLog method to be propagated to loggers that need it.

    Note that AWSDDLog’s flushLog method is invoked automatically when the application quits, and it may be also invoked manually by the developer prior to application crashes, or other such reasons.

    Declaration

    Objective-C

    - (void)flush;

    Swift

    optional func flush()

  • Each logger is executed concurrently with respect to the other loggers. Thus, a dedicated dispatch queue is used for each logger. Logger implementations may optionally choose to provide their own dispatch queue.

    Declaration

    Objective-C

    @optional
@property (nonatomic, strong, readonly) dispatch_queue_t _Nonnull loggerQueue;

    Swift

    optional var loggerQueue: dispatch_queue_t { get }

  • If the logger implementation does not choose to provide its own queue, one will automatically be created for it. The created queue will receive its name from this method. This may be helpful for debugging or profiling reasons.

    Declaration

    Objective-C

    @optional
@property (nonatomic, copy, readonly) AWSDDLoggerName _Nonnull loggerName;

    Swift

    optional var loggerName: AWSDDLoggerName { get }