How do I get the default temporary directory on Mac OS X?

Question

I'd like to create some directories of data for some unit tests and I'd like these directories to be in the default temporary directory for the user.

I could just create a subdir under /tmp I suppose, but I don't want to make an assumption about how somebody has set up their own machine.

I'm planning on writing the test data on the fly, which is why I'd like to put this into a temporary directory.

Answer 1

Don't use tmpnam() or tempnam(). They are insecure (see the man page for details). Don't assume /tmp. Use NSTemporaryDirectory() in conjunction with mkdtemp(). NSTemporaryDirectory() will give you a better directory to use, however it can return nil. I've used code similar to this:

NSString * tempDir = NSTemporaryDirectory();
if (tempDir == nil)
    tempDir = @"/tmp";

NSString * template = [tempDir stringByAppendingPathComponent: @"temp.XXXXXX"];
NSLog(@"Template: %@", template);
const char * fsTemplate = [template fileSystemRepresentation];
NSMutableData * bufferData = [NSMutableData dataWithBytes: fsTemplate
                                                   length: strlen(fsTemplate)+1];
char * buffer = [bufferData mutableBytes];
NSLog(@"FS Template: %s", buffer);
char * result = mkdtemp(buffer);
NSString * temporaryDirectory = [[NSFileManager defaultManager]
        stringWithFileSystemRepresentation: buffer
                                    length: strlen(buffer)];

You can now create files inside temporaryDirectory. Remove the NSLogs for production code.

Answer 2

Looking back at this question there and the documentation for NSTemporaryDirectory(), if you are using 10.6 or above, then you are recommended to use the URLForDirectory:inDomain:appropriateForURL:create:error: method from NSFileManager for a more flexible method of creating directories.

And it returns a URL instead of a string path, which is another thing we're recommended to use.