MMMLog

Very simple logging for iOS.

(This is a part of MMMTemple suite of iOS libraries we use at MediaMonks.)

Splitting a logging framework into “formatters”, “loggers”, and “entries” makes it appear more flexible and might be a nice exercise in OO design, but is not required in a typical mobile app. We’ve been using MMMLog in several production projects through the years and it was enough.

Installation

Podfile

source 'https://github.com/mediamonks/MMMSpecs.git'
source 'https://github.com/CocoaPods/Specs.git'
...
pod 'MMMLog'

(Use ‘MMMLog/ObjC’ when Swift wrappers are not needed.)

Swift Package Manager

dependencies: [
    .package(url: "https://github.com/mediamonks/MMMLog", from: "0.5.1")
]

Or add the dependency through Xcode (> 11.4) by going to File > Swift Packages > Add Package Dependency...

Usage

ObjC:

MMM_LOG_INFO(@"Base URL: %@", url);

Swift:

MMMLogInfo(self, "Base URL: \(url)")

Both will appear like this in Xcode console:

|17:00:13.11|  - AppDelegate#260  Base URL: https://mediamonks.com/

Levels

‘Trace’, ‘info’, and ‘error’ versions of these macros/functions are supported (e.g. MMM_LOG_TRACE()/MMLogTrace()).

There is additional MMM_LOG_TRACE_METHOD()/MMMLogTraceMethod() macro/function, tracing the current method/function name:

override func viewDidAppear(_ animated: Bool) {
    MMMLogTraceMethod(self)
...

Leading to something like this in Xcode console:

|17:00:13.15|    ViewController#ad0  Entering viewDidAppear(_:)

Context

The Obj-C class instance calling a macro or the first parameter of a Swift function are used to identify the “source” or “context” of the message. By default it appears before the message:

|17:00:13.11|  - AppDelegate#260  Base URL: https://mediamonks.com/

It’s possible to override the context, see mmm_instanceNameForLogging method in Obj-C and/or MMMLogSource protocol in Swift.

Redirection

All messages are directed to NSLog() by default but this can be overriden with MMMLogOverrideOutputWithBlock()/MMMLogOverrideOutput() somewhere early on startup, e.g.:

MMMLogOverrideOutput { (level, context, message) in

    // OSLog.
    MMMLogOutputToOSLog(level, context, message)

    let formattedMessage = MMMLogFormat(level, context, message)

    // Crashlytics.
    withVaList([formattedMessage]) { CLSLogv("%@", $0) }

    // Instabug.
    switch level {
    case .trace:
        IBGLog.log(formattedMessage)
    case .info:
        IBGLog.logInfo(formattedMessage)
    case .error:
        IBGLog.logError(formattedMessage)
    }

    ...
}

(See MMMLogFormat(), MMMLogOutputToOSLog(), MMMLogOutputToConsole() helpers.)

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