How to check if a directory exists in Objective-C - iphone

Question

I guess this is a beginner's problem, but I was trying to check if a directory exists in my Documents folder on the iPhone. I read the documentation and came up with this code which unfortunately crashed with EXC_BAD_ACCESS in the BOOL fileExists line:
-(void)checkIfDirectoryAlreadyExists:(NSString *)name
{
NSFileManager *fileManager = [[NSFileManager alloc] init];
NSString *path = [[self documentsDirectory] stringByAppendingPathComponent:name];
BOOL fileExists = [fileManager fileExistsAtPath:path isDirectory:YES];
if (fileExists)
{
NSLog(#"Folder already exists...");
}
}
I don't understand what I've done wrong? It looks all perfect to me and it certainly complies with the docs, not? Any revelations as to where I went wrong would be highly appreciated! Thanks.
UPDATED:
Still not working...
-(void)checkIfDirectoryAlreadyExists:(NSString *)name
{
NSFileManager *fileManager = [[NSFileManager alloc] init];
NSString *path = [[self documentsDirectory] stringByAppendingPathComponent:name];
BOOL isDir;
BOOL fileExists = [fileManager fileExistsAtPath:path isDirectory:&isDir];
if (fileExists)
{
if (isDir) {
NSLog(#"Folder already exists...");
}
}
}

Answer 1

Take a look in the documentation for this method signature:
- (BOOL)fileExistsAtPath:(NSString *)path isDirectory:(BOOL *)isDirectory
You need a pointer to a BOOL var as argument, not a BOOL itself. NSFileManager will record if the file is a directory or not in that variable. For example:
BOOL isDir;
BOOL exists = [fm fileExistsAtPath:path isDirectory:&isDir];
if (exists) {
/* file exists */
if (isDir) {
/* file is a directory */
}
}

Answer 2

Just in case somebody needs a getter, that creates a folder in Documents, if it doesn't exist:
- (NSString *)folderPath
{
if (! _folderPath) {
NSString *folderName = #"YourFolderName";
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [documentPaths objectAtIndex:0];
_folderPath = [documentsDirectoryPath stringByAppendingPathComponent:folderName];
// if folder doesn't exist, create it
NSError *error = nil;
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOL isDir;
if (! [fileManager fileExistsAtPath:_folderPath isDirectory:&isDir]) {
BOOL success = [fileManager createDirectoryAtPath:_folderPath withIntermediateDirectories:NO attributes:nil error:&error];
if (!success || error) {
NSLog(#"Error: %#", [error localizedDescription]);
}
NSAssert(success, #"Failed to create folder at path:%#", _folderPath);
}
}
return _folderPath;
}

Answer 3

I have a Utility singleton class that I use for things like this. Since I can’t update my database if it remains in Documents, I copy my .sqlite files from Documents to /Library/Private Documents using this code. The first method finds the Library. The second creates the Private Documents folder if it doesn’t exist and returns the location as a string. The second method uses the same file manager method that #wzboson used.
+ (NSString *)applicationLibraryDirectory {
return [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) lastObject];
}
+ (NSString *)applicationLibraryPrivateDocumentsDirectory {
NSError *error;
NSString *PrivateDocumentsDirectory = [[self applicationLibraryDirectory] stringByAppendingPathComponent:#"Private Documents"];
BOOL isDir;
if (! [[NSFileManager defaultManager] fileExistsAtPath:PrivateDocumentsDirectory isDirectory:&isDir]) {
if (![[NSFileManager defaultManager] createDirectoryAtPath:PrivateDocumentsDirectory
withIntermediateDirectories:NO
attributes:nil
error:&error]) {
NSLog(#"Create directory error: %#", error);
}
}
return PrivateDocumentsDirectory;
}
I use it like this in my persistent store coordinator initialization. The same principal applies to any files though.
NSString *libraryDirectory = [Utilities applicationLibraryPrivateDocumentsDirectory];
NSString *sourcePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:sqliteName];
NSString *destinationPath = [libraryDirectory stringByAppendingPathComponent:sqliteName];