A minimal wrapper around Apple's unified logging system.

By default support for the log crate is provided, but if you would prefer just to use the lower level bindings you can disable the default features.

When making use of targets (info!(target: "t", "m");), you should be aware that a new log is allocated and stored in a map for the lifetime of the program. I expect log allocations are extremely small, but haven't attempted to verify it.

Logging example

This is behind the logger feature flag and is enabled by default.

fn main() {
    OsLogger::new("com.example.test")
        .level_filter(LevelFilter::Debug)
        .category_level_filter("Settings", LevelFilter::Trace)
        .init()
        .unwrap();

    // Maps to OS_LOG_TYPE_DEBUG
    trace!(target: "Settings", "Trace");

    // Maps to OS_LOG_TYPE_INFO
    debug!("Debug");

    // Maps to OS_LOG_TYPE_DEFAULT
    info!(target: "Parsing", "Info");

    // Maps to OS_LOG_TYPE_ERROR
    warn!("Warn");

    // Maps to OS_LOG_TYPE_FAULT
    error!("Error");
}

Limitations

Most of Apple's logging related functions are macros that enable some optimizations as well as providing contextual data such as source file location.

By wrapping the macros for use from Rust, we lose those benefits.

Attempting to work around this would involve digging in to opaque types, which would be an automatic or eventual rejection from the App store.