How do I debug with NSLog(@“Inside of the iPhone Simulator”)?

Question

I\'m used to programming and having log messages be viewable. I know you used to be able to use NSLog() to trace out messages when debugging Cocoa applications.

Answer 1

In my project I have a customised solution based on DebugOutput.m This adds the file & line number to the debug output, making it easier to identify where that output text is coming from, while still keeping it brief.

I've augmented the standard solution with a debug mask, so that I can switch debugging on and off for particular areas of functionality in my app. In Debug.h, I have

typedef enum {
kDebugMaskAp- = 1,
kDebugMaskXMLParser = 1 << 1,
kDebugMaskNetwork = 1 << 2,
kDebugMaskAnalytics = 1 << 3,
kDebugMaskCache = 1 << 4,
} debugBitMask;

#define debugForComponent(mask,format,...) if( currentDebugMask() & mask) [[DebugOutput sharedDebug]  output:__FILE__ lineNumber:__LINE__ input:(format), ##__VA_ARGS__]

And in Debug.m

-(void)output:(char*)fileName lineNumber:(int)lineNumber input:(NSString*)input, ...
{
  va_list argList;
  NSString *filePath, *formatStr;

  // Build the path string
  filePath = [[NSString alloc] initWithBytes:fileName length:strlen(fileName) encoding:NSUTF8StringEncoding];

  // Process arguments, resulting in a format string
  va_start(argList, input);
  formatStr = [[NSString alloc] initWithFormat:input arguments:argList];
  va_end(argList);

  // Call NSLog, prepending the filename and line number
  NSLog(@"File:%s Line:%d %@",[((DEBUG_SHOW_FULLPATH) ? filePath : [filePath lastPathComponent]) UTF8String], lineNumber, formatStr);

  [filePath release];
  [formatStr release];
}

In the application, calls look something like this:

debugForComponent(kDebugMaskApp,@"Request failed - error %@", [error localizedDescription]);