iOS Swift :将NSLog调用路由到文件

import Foundation

func logToFile(_ message: String, file: String = #file, line: Int = #line, function: String = #function) {
    let fileName = (file as NSString).lastPathComponent
    let logMessage = "\(Date()): \(fileName):\(line) \(function) - \(message)\n"
    
    if let documentDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first {
        let logFileURL = documentDirectory.appendingPathComponent("app.log")
        
        do {
            let fileHandle = try FileHandle(forWritingTo: logFileURL)
            fileHandle.seekToEndOfFile()
            fileHandle.write(logMessage.data(using: .utf8)!)
            fileHandle.closeFile()
        } catch {
            print("Failed to write to log file: \(error)")
        }
    }
}

logToFile("This is a log message.")