The utility needs somewhere to save the file for the persistent store. This section illustrates one way to identify and if necessary create an appropriate directory. Although it is a useful abstraction for the utility, this is not directly relevant to Core Data, so no additional explanation is given. For details about locating system directories, see Low-Level File Management Programming Topics.
This section illustrates a simple means to identify and if necessary create a directory (in ~/Library/Logs—the Logs directory in your home directory) in which to save the file for the persistent store.
In the main source file, before main() declare a function, applicationLogDirectory(), that returns an NSURL object, then after main() implement it as follows:
NSURL *applicationLogDirectory() { |
NSString *LOG_DIRECTORY = @"CDCLI"; |
static NSURL *ald = nil; |
if (ald == nil) { |
NSFileManager *fileManager = [[NSFileManager alloc] init]; |
NSError *error = nil; |
NSURL *libraryURL = [fileManager URLForDirectory:NSLibraryDirectory inDomain:NSUserDomainMask |
appropriateForURL:nil create:YES error:&error]; |
if (libraryURL == nil) { |
NSLog(@"Could not access Library directory\n%@", [error localizedDescription]); |
} |
else { |
ald = [libraryURL URLByAppendingPathComponent:@"Logs"]; |
ald = [ald URLByAppendingPathComponent:LOG_DIRECTORY]; |
NSDictionary *properties = [ald resourceValuesForKeys: |
[NSArray arrayWithObject:NSURLIsDirectoryKey] error:&error]; |
if (properties == nil) { |
if (![fileManager createDirectoryAtPath:[ald path] |
withIntermediateDirectories:YES attributes:nil error:&error]) { |
NSLog(@"Could not create directory %@\n%@", |
[ald path], [error localizedDescription]); |
ald = nil; |
} |
} |
} |
} |
return ald; |
} |
In the main function, after the invocation of the managedObjectModel function, invoke applicationLogDirectory(); if it returns nil, exit.
if (applicationLogDirectory() == nil) { |
exit(1); |
} |
Build and run the utility. It should compile without warnings. The application log directory should be created correctly, and no errors should be logged.
Last updated: 2010-05-24