记录到 Xcode 控制台和文件

Question

我正在尝试将我的日志同时发送到 Xcode 控制台和带有 Swift 的文件。我找到的解决方案要么是控制台，要么是仅重定向到文件。

如何让日志转到两者？

注意：一些日志来自我应用程序中的其他 3rd 库和框架，而不仅仅是 Swift 的print()。因此，在应用程序上使用宏或日志记录框架(如CocoaLumberjack(将无济于事。

例如，这会在调用时将控制台中的所有日志重定向到文件，然后控制台变为空

  func logToFile() {
    var paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentsDirectory = paths[0]
    let fileName = "app_log.txt"
    let logFilePath = (documentsDirectory as NSString).appendingPathComponent(fileName)
    freopen(logFilePath.cString(using: String.Encoding.ascii)!, "a+", stderr)
    freopen(logFilePath.cString(using: String.Encoding.ascii)!, "a+", stdin)
    freopen(logFilePath.cString(using: String.Encoding.ascii)!, "a+", stdout)
  }

Answer 1

我已经稍微扩展了您的方法，现在您将给定的字符串写入输出文件并将其记录到控制台。

我喜欢有另一个函数，它处理给定的字符串，使用像这样的参数

__FILE__ - String - The name of the file in which it appears.
__LINE__ - Int - The line number on which it appears.
__COLUMN__ - Int - The column number in which it begins.
__FUNCTION__ - String - The name of the declaration in which it appears.

扩展方法现在可能如下所示。

func logToFile(message: String) -> Void {
        var paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
        let documentsDirectory = paths[0]
        let fileName = "app_log.txt"
        let logFilePath = (documentsDirectory as NSString).appendingPathComponent(fileName)
        let fileUrl = URL(fileURLWithPath: logFilePath)
        var error:NSError?
        // simply create the file, here you could add first line or something
        // just make sure it exists
        if (!FileManager.default.fileExists(atPath: logFilePath)) {
            let data = new Data();
            do {
                try data.write(to:fileUrl , options: .atomic)
            } catch {
                println("Can't create file (error)")
            }
        }
        // start writing
        if let fileHandle = NSFileHandle(forWritingToURL: fileurl, error: &error) {
            let data = message.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
            fileHandle.seekToEndOfFile()
            fileHandle.writeData(data)
            fileHandle.closeFile()
        }
        else {
        }
        // Now also print the result to console
        print(message)
    }