signpost_loadArticles_with_signposts.swift

import os.log
import os.signpost

let networkLog = OSLog(subsystem: "com.example.app.reader", category: "Articles")
let signpostID = OSSignpostID(log: networkLog)

func loadArticles() throws -> [Article] {
    let decoder = JSONDecoder()

    return try files.map { file in
    
        os_signpost(type: .begin, log: networkLog, name: "Read File", 
                    signpostID: signpostID,"%{public}s", file.path)
        let data = try file.read()
        os_signpost(type: .end, log: networkLog, name: "Read File", 
                    signpostID: signpostID,"%{public}s", file.path)

        os_signpost(type: .begin, log: networkLog, name: "Parse Article from File", 
                    signpostID: signpostID,"%{public}s", file.path)
        let article = try decoder.decode(Article.self, from: data)
        os_signpost(type: .end, log: networkLog, name: "Parse Article from File", 
                    signpostID: signpostID,"%{public}s", file.path)
                
        return article
    }
}