Sample code to access OSLogStore on iOS and macOS.

OSLogTest.swift

let subsystem = "com.steipete.LoggingTest"

func getLogEntries() throws -> [OSLogEntryLog] {
    // FB8269189: OSLogStore does not work iOS.
    let logStore = try OSLogStore(scope: .currentProcessIdentifier)
    let oneHourAgo = logStore.position(date: Date().addingTimeInterval(-3600))

    #if os(macOS)
        let allEntries = try logStore.getEntries(at: oneHourAgo)
    #else
        // FB8518476: The Swift shims for for the entries enumerator are missing.
        let allEntries = try Array(logStore.__entriesEnumerator(position: oneHourAgo, predicate: nil))
    #endif

    // FB8518539: Using NSPredicate to filter the subsystem doesn't seem to work.
    return allEntries
        .compactMap { $0 as? OSLogEntryLog }
        .filter { $0.subsystem == subsystem }
}