Write log content into text file using freopen not working with Swift

Question

I want to write every print() content into a text file in Swift 3.0. It was working fine in Objective-C but not worked in Swift 3.0. I am using the code as below,

    func redirectLogToDocuments() {

    let docDirectory: NSString = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)[0] as NSString
    let logpath = docDirectory.appendingPathComponent("Logfile.txt")

    freopen(logpath.cString(using: String.Encoding.utf8)!, "a+", stdin)
    freopen(logpath.cString(using: String.Encoding.utf8)!, "a+", stdout)
    freopen(logpath.cString(using: String.Encoding.utf8)!, "a+", stderr)                
}

Please help me.

Works for me (but compare https://stackoverflow.com/a/41680336/1187415). – What is the concrete problem? And you really want to redirect **stdin** to/from the same file? — Martin R, Jul 18 '17 at 11:10

score 6 · Accepted Answer · answered Jul 31 '18 at 10:52

 func redirectLogToDocuments() {
    let allPaths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentsDirectory = allPaths.first!
    let pathStringComponent = "/" + LoggingConstants.LogFileName + "." + LoggingConstants.LogFileType
    let pathForLog = (documentsDirectory as NSString).appending(pathStringComponent)
    freopen(pathForLog.cString(using: String.Encoding.ascii)!, "a+", stderr)
}

Use the above method in didFinishLaunching() and after that use NSLog() statements instead of print() and you will get what you want.

Write log content into text file using freopen not working with Swift

1 Answers1