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Unity Engine

Native plug-in API for logging

Write Unity log messages from native plug-ins.
Read time 2 minutesLast updated 12 days ago
Write to the Unity logs from your native plug-in code using the 
IUnityLog
interface. Low-level native APIs for logging are provided in the 
IUnityLog.h
header file, located in the PluginAPI folder.
The file contains a single 
Log
function with the following decalaration:
void(UNITY_INTERFACE_API * Log)(UnityLogType type, const char* message, const char *fileName, const int fileLine);
You can call this function directly as follows:
s_UnityLog->Log(kUnityLogTypeLog, "Here is a regular log", __FILE__, __LINE__);
However, for convenience the native logging API defines the following macros that wrap different log-level calls to the 
Log
function:

Macro

Description

UNITY_LOG(PTR_, MSG_)
Uses the log interface passed as a pointer (
PTR_
) to write the provided char* 
MSG_
as a regular log message. Equivalent to the managed API Debug.Log.
UNITY_LOG_WARNING(PTR_, MSG_)
Uses the log interface passed as a pointer (
PTR_
) to write the provided char* 
MSG_
as a warning-level log message. Equivalent to the managed API Debug.LogWarning.
UNITY_LOG_ERROR(PTR_, MSG_)
Uses the log interface passed as a pointer (
PTR_
) to write the provided char* 
MSG_
as an error-level log message. Equivalent to the managed API Debug.LogError.
The following code example implements the 
IUnityLog
interface in C++ and uses these predefined macros to write different levels of log output:
#include "IUnityLog.h"static IUnityLog* s_UnityLog = NULL;// Additional macros to include file and line number from the native code#define UNITY_LOG_STRINGIZE_DETAIL(x) #x#define UNITY_LOG_STRINGIZE(x) UNITY_LOG_STRINGIZE_DETAIL(x)#define COMPOSE(MESSAGE) "[" __FILE__ ":" UNITY_LOG_STRINGIZE(__LINE__) "] " MESSAGE#define NATIVE_LOG(PTR, MESSAGE) UNITY_LOG(PTR, COMPOSE(MESSAGE))#define NATIVE_WARNING(PTR, MESSAGE) UNITY_LOG_WARNING(PTR, COMPOSE(MESSAGE))#define NATIVE_ERROR(PTR, MESSAGE) UNITY_LOG_ERROR(PTR, COMPOSE(MESSAGE))// Unity plugin load eventextern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API UnityPluginLoad(IUnityInterfaces * unityInterfacesPtr){	s_UnityLog = unityInterfacesPtr->Get<IUnityLog>();}// Unity plugin unload eventextern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API UnityPluginUnload(){	s_UnityLog = nullptr;}extern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API GenerateLog(){	// Output different log level messages to the Unity console	UNITY_LOG(s_UnityLog, "Regular log message");	UNITY_LOG_WARNING(s_UnityLog, "Warning log message");	UNITY_LOG_ERROR(s_UnityLog, "Error log message");	// Wrap log functions to provide native file and line number in output	NATIVE_LOG(s_UnityLog, "Regular log with native file name and line number");	NATIVE_WARNING(s_UnityLog, "Warning log with native file name and line number");	NATIVE_ERROR(s_UnityLog, "Error log with native file name and line number");}
Note
The additional macros to embed the native file and line number in the message are a workaround for a known issue in which Unity fails to include the information when the 
Log
function is invoked via 
UNITY_LOG
and equivalents.

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