logging in iPhone Applications

NSData *dataToWrite = [[NSString stringWithString:@"String to write"] dataUsingEncoding:NSUTF8StringEncoding];

NSString *docsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *path = [docsDirectory stringByAppendingPathComponent:@"fileName.txt"];

// Write the file
[dataToWrite writeToFile:path atomically:YES];

// Read the file
NSString *stringFromFile = [[NSString alloc] initWithContentsOfFile:path]; 

// Check if file exists
NSFileManager *fileManager = [NSFileManager defaultManager];
[fileManager fileExistsAtPath:path]; // Returns a BOOL   

// Remove the file
[fileManager removeItemAtPath:path error:NULL];

// Cleanup
[stringFromFile release];
[fileManager release];

White log into the log-file

+ (void)logGenenalInfo:(NSString *)data {
 NSString *docsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
 NSString *path = [docsDirectory stringByAppendingPathComponent:@"GeneralFile.txt"];
 
 // Check if file exists
 NSFileManager *fileManager = [NSFileManager defaultManager];
 if ([fileManager fileExistsAtPath:path]) {
  // Read the file
  NSString *stringFromFile = [[NSString alloc] initWithContentsOfFile:path];
  data = [stringFromFile stringByAppendingFormat:@" %@",data];
 }
 NSData *dataToWrite = [data dataUsingEncoding:NSUTF8StringEncoding];
 // Write the file
 [dataToWrite writeToFile:path atomically:YES];
 [fileManager release];
}

Clean the Log

+ (void)cleanAllLog {
 NSFileManager *fileManager = [NSFileManager defaultManager];
 
 NSString *docsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
 NSString *gePath = [docsDirectory stringByAppendingPathComponent:@"GeneralFile.txt"];
 
 
 // Check if file exists then Remove the file
 if ([fileManager fileExistsAtPath:gePath]) // Returns a BOOL    
  [fileManager removeItemAtPath:gePath error:NULL];
 
 [fileManager release];
}

Get the program information

DateTime\tMessage\tData\tfileNameAndLineNumber

[LogFileHelper logGenenalInfo:
[NSString stringWithFormat:@"function %s, line %d \n"
,__FUNCTION__,__LINE__]];