Get Debug.Log output in the working iOS build

You can use log callbacks to save log to file, or send it to your server.

 public class LogHandler : MonoBehaviour
 {
     private StreamWriter _writer;
     void Awake()
     {
         _writer = File.AppendText("log.txt");    
         _writer.Write("\n\n=============== Game started ================\n\n");
         DontDestroyOnLoad(gameObject);
         Application.RegisterLogCallback(HandleLog);
     }
 
     private void HandleLog(string condition, string stackTrace, LogType type)
     {
         var logEntry = string.Format("\n {0} {1} \n {2}\n {3}"
             , DateTime.Now, type, condition, stackTrace);
         MyServer.SendLog(logEntry);
         _writer.Write(logEntry);
     }
 
     void OnDestroy()
     {
         _writer.Close();
     }
 }

Hey so -- good answer by @Mozgold but -- well, first off let me note that Application.RegisterLogCallback has now been replaced -- any one looking to use @Mozgold's answer should use Application.logMessageReceivedThreaded or Application.logMessageReceived -- see this thread http://answers.unity3d.com/questions/1009660/how-to-use-applicationlogmessagereceived-for-loggi.html

I had the same problem, but preferred instead to use a bridge to pipe Debug.Log messages to NSLog. The downside of this approach is that, in XCode's console, you see the messages twice. The advantage is that, when running a TestFlight'd build, I see the messages live as they happen in XCode's Window / Devices log when the app is running on my selected device.

STEP 1 -- register a callback so that Debug.Log's are piped to method in my iOS plugin

     public void OnEnable() {
         // Debug.LogWarning("------ ------ Registered log callback----- ---------");
         Application.logMessageReceived += IOSPlugin.LogToiOS;
     }
 
     public void OnDisable() {
         Application.logMessageReceived -= IOSPlugin.LogToiOS;
     }

STEP 2 -- implement method in my iOSPlugin to pipe these calls to the native app

 using UnityEngine;
 using System.Collections;
 using System.Runtime.InteropServices;
 
 public class IOSPlugin : MonoBehaviour {
 
     #if UNITY_IPHONE
     [DllImport ("__Internal")]
     private static extern void _logToiOS(string debugMessage);
     #endif
 
     public static void LogToiOS(string logString, string stackTrace, LogType type) {
         // We check for UNITY_IPHONE again so we don't try this if it isn't iOS platform.
         #if UNITY_IPHONE
         // Now we check that it's actually an iOS device/simulator, not the Unity Player. You only get plugins on the actual device or iOS Simulator.
         if (Application.platform == RuntimePlatform.IPhonePlayer) {
             _logToiOS(logString + "\n===============\n" + stackTrace);
         }
         #endif
     }
 }

STEP 3 -- implement a method in my iOS app's AppController.mm to pipe this to NSLog -- you should be able to just directly drop this in your AppController.mm and be all set

 extern "C" {
   
     void _logToiOS(const char* debugMessage) {
          NSLog(@"Received _logToiOS %@", [NSString stringWithUTF8String:debugMessage]);
     }
 
 }

First build your iOS app with "Development Build" enabled. In Unity 4, Debug.Log() output is shown in the XCode's debug Console. Notice that this is NOT the Console in the Organizer, which shows the device events, but it's the Console that is shown at the bottom of the main window, which is called Debug area. The Organizer's Device Logs is useful to obtain the crash logs when the app is executing out of XCode.

You can check that with another option. Connect you phone to your MAC which have xCode install. Now open xCode and from xCode open Organizer. From Organizer select **Devices*tab and in that you can see you device in that. And from your selected device select Console* in that you can see the device log.

You can redirect NSLog (and so, what you write with Debug.Log, will also be redirected) to file adding something like that to your native ios code:

 - (void)redirectLogToDocument
 {
      NSArray *allPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
      NSString *documentsDirectory = [allPaths objectAtIndex:0];
      NSString *pathForLog = [documentsDirectory stringByAppendingPathComponent:@"yourFile.txt"];
 
      NSLog(@"redirectLogToDocument: %@", pathForLog);
     
      freopen([pathForLog cStringUsingEncoding:NSASCIIStringEncoding],"a+",stderr);
     freopen([pathForLog cStringUsingEncoding:NSASCIIStringEncoding],"a+",stdout);
 }
 
 // usage:
 
     if (!isatty(STDERR_FILENO)) { // if debugger not attached
         [self redirectLogToDocument]; // redirect logs
     }
 

Then you can take your file using Window -> Devices & Simulators -> select your device -> select your app -> press settings button below -> select "download container" from dropdown. xcappdata file will be saved. Reveil in finder, click right mouse button, click "show package contents", then go to Documents folder. There will be your file.

Screenshot better describes that: https://stackoverflow.com/a/6121649/884195

Based on: https://stackoverflow.com/a/8379047/884195 https://stackoverflow.com/a/9620429/884195