How to use asl.h in swift-ios files

Question

I am new to ios / swift. I would like to use c-function entries from asl.h in fast files. Anyone? I am googled and people seem to write their own quick logging classes. No disrespect, but I would like to use only asl. That is, the fast one doesn't like #include <asl.h> and I don't like the fact that I'm just calling asl_log(NULL, NULL, ASL_LEVEL_INFO, "Hello World!");

Answer 1

Thanks, and with the help of http://doing-it-wrong.mikeweller.com/2012/07/youre-doing-it-wrong-1-nslogdebug-ios.html I made the following changes:

The BRASL.h file has been added to the project with the following contents:

 // // BRASL.h // #ifndef BRASL_h #define BRASL_h #import <asl.h> #import <Foundation/Foundation.h> // Define which loglevel is necessary for deployment and development // ================================================================= // Used to conditionally implement the log functions. All log // functions are defined so the compiler does not complain. But only // those logfunctions that are used will contain code. // ================================================================= #ifndef BRASL_LOG_LEVEL // DEBUG is set in the project build-settings #if DEBUG == 1 // Set logging level for development #define BRASL_LOG_LEVEL ASL_LEVEL_DEBUG #else // Set logging level for deployment #define BRASL_LOG_LEVEL ASL_LEVEL_NOTICE #endif #endif // Define the log functions // ======================== void aslEmergency(NSString *string); void aslAlert(NSString *string); void aslCritical(NSString *string); void aslError(NSString *string); void aslWarning(NSString *string); void aslNotice(NSString *string); void aslInfo(NSString *string); void aslDebug(NSString *string); #endif 

Then the corresponding .m file is added with:

 // // BRASL.h // #import "BRASL.h" // We need this to set asl up to also write the information to the debugger // ======================================================================== static void AddStderrOnce() { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ asl_add_log_file(NULL, STDERR_FILENO); }); } // Implement the log functions where necessary // =========================================== #if BRASL_LOG_LEVEL >= ASL_LEVEL_EMERG void aslEmergency(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_EMERG, "%s", [string UTF8String]); } #else void aslEmergency(NSString *string) {} #endif #if BRASL_LOG_LEVEL >= ASL_LEVEL_ALERT void aslAlert(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_ALERT, "%s", [string UTF8String]); } #else void aslAlert(NSString *string) {} #endif #if BRASL_LOG_LEVEL >= ASL_LEVEL_CRIT void aslCritical(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_CRIT, "%s", [string UTF8String]); } #else void aslCritical(NSString *string) {} #endif #if BRASL_LOG_LEVEL >= ASL_LEVEL_ERR void aslError(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_ERR, "%s", [string UTF8String]); } #else void aslError(NSString *string) {} #endif #if BRASL_LOG_LEVEL >= ASL_LEVEL_WARNING void aslWarning(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_WARNING, "%s", [string UTF8String]); } #else void aslWarning(NSString *string) {} #endif #if BRASL_LOG_LEVEL >= ASL_LEVEL_NOTICE void aslNotice(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_NOTICE, "%s", [string UTF8String]); } #else void aslNotice(NSString *string) {} #endif #if BRASL_LOG_LEVEL >= ASL_LEVEL_INFO void aslInfo(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_INFO, "%s", [string UTF8String]); } #else void aslInfo(NSString *string) {} #endif #if BRASL_LOG_LEVEL >= ASL_LEVEL_DEBUG void aslDebug(NSString *string) { AddStderrOnce(); asl_log(NULL, NULL, ASL_LEVEL_DEBUG, "%s", [string UTF8String]); } #else void aslDebug(NSString *string) {} #endif 

And of course the bridge file

 // // Use this file to import your target public headers that you would like to expose to Swift. // #import "BRASL.h" 

Then in my quick code I can use for example:

 aslInfo("Initializing managed object context") 

So far so good, it seems to work as advertised :)

Answer 2

So far, the easiest way I have found the following ( it works for any c-libraries ):

Step-1: File-A new Objective-C file, for example. MyBridgeToACLib.h, MyBridgeToACLib.m

Step 2: in MyBridgeToACLib.h

 #import <Foundation/Foundation.h> @interface MyBridgeToACLib : NSObject // here you need to declare a function for each c-function you want to call from swift, eg : + (void) debug:(NSString*) nsStr; + (void) debug:(NSString*) nsStr secondValue:(NSInteger) nsInt; @end 

Step 3: in MyBridgeToACLib.m

 #include <asl.h> // or any c-library you need to call from Swift #import "MyBridgeToACLib.h" @implementation MyBridgeToACLib + (void) debug:(NSString*) nsStr { // here you need to convert from Objective-C types to C-types, eg NSString to char* const char *cStr = [nsStr UTF8String]; printf("%s\n", cStr); // call your c-functions asl_log(NULL, NULL, ASL_LEVEL_DEBUG, "%s", cStr); } + (void) debug:(NSString*) nsStr secondValue:(NSInteger) nsInt { const char *cStr = [nsStr UTF8String]; long cInt = nsInt; printf("%s%li\n", cStr, cInt); asl_log(NULL, NULL, ASL_LEVEL_DEBUG, "%s%li", cStr, cInt); } @end 

Step 4: Configure the following "MyProjectName-Bridging-Header.h". Google "Xcode Bridging-Header" for instructions.

  // Swift and Objective-C in the Same Project //https://developer.apple.com/library/ios/documentation/swift/conceptual/buildingcocoaapps/MixandMatch.html // // Here import all of your "Bridge"-headers #import "MyBridgeToACLib.h" 

Answer 3

Here are some open source projects that might interest you:

• CleanroomASL - a low-level, but Swiftified API for reading and writing to the Apple System Log

• CleanroomLogger - A high-level Swift logging API that supports writing to ASL

• AppleSystemLogSwiftPackage - A Package Manager (SPM) declaration that allows you to import ASL from your code. (Note that SPM is only building for Mac OS X at the moment, so now this will not help you with iOS.)

Based on what you wrote, I suspect that the CleanroomLogger project will be most suitable for your use.

Hope you find this helpful

E.

Full disclosure: I contributed to each of these projects.