coredata problem nsurl may not respond to stringByAppendingPathComponent - iphone

Question

I had some problems after starting a new coredata project with the xcode 3.2.5... my previous projects with core data (in previous xcode) worked fine, so I dont know what is the difference??
so the error I get when I build and go to the view that calls the core data is>
*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'
the strange thing is that in my *AppDelegate.m, in (edited thanks Rog but still not working!)
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
if (persistentStoreCoordinator_ != nil) {
return persistentStoreCoordinator_;
}
NSString *storePath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent: #"staff.sqlite"];
NSURL *storeUrl = [NSURL fileURLWithPath:storePath]; //new position for the storeUrl!
// Put down default db if it doesn't already exist
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:storePath]) {
NSString *defaultStorePath = [[NSBundle mainBundle] pathForResource:#"staff" ofType:#"sqlite"];
if (defaultStorePath) {
[fileManager copyItemAtPath:defaultStorePath toPath:storePath error:NULL];
}
}
in the
NSString *storePath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent: #"staff.sqlite"];
I get the warning
NSURL may not respond to '-stringByAppendingPathComponent'
I option + click this stringByAppendingPathComponent and get (Symbol not found!!!!)
but in other projects I do option + click in the same and get the definition!!
so is this warning related to my error??
how to fix it???
Edit,
included this in my viewDidLoad
NSLog(#"path= %#", [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]) ;
which gives me in console:
path= /Users/mkss9/Library/Application Support/iPhone Simulator/4.2/Applications/2F364C20-2B87-4ABB-AA3E-FB6F7C15096F/Documents
please!, Im getting crazy !!
thank you!

Answer 1

Some SDK Version ago (I don't know for sure when they did) apple changed the return type of applicationDocumentsDirectory in their project templates.
When you create a new project it looks like this:
/**
Returns the URL to the application's Documents directory.
*/
- (NSURL *)applicationDocumentsDirectory {
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
in older templates it looked like this:
/**
Returns the path to the application's documents directory.
*/
- (NSString *)applicationDocumentsDirectory {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
return basePath;
}
and in between those two it looked like this:
/**
Returns the path to the application's Documents directory.
*/
- (NSString *)applicationDocumentsDirectory {
return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}
So you have to be careful, because all the old code that relies on applicationDocumentsDirectory returning a NSString won't work with newer templates.
And you can't just replace the new version with the older version because this would result in a change in your core data methods.
So I would suggest you to write your own method for returning the documents directory. Apple changes their applicationDocumentsDirectory quite often.

Answer 2

I would imagine it's because -applicationDocumentsDirectory returns an NSURL * instead of an NSString *.

Answer 3

Firstly you need to make sure you applicationDocumentsDirectory method is returning a NSString.
Once that's out of the way, the subsequent crash is because you are passing a path and filename that don't exist yet.
So if you move your NSURL *storeUrl = [NSURL fileURLWithPath:storePath]; to after the code that checks for an existing file and puts a default one in case it doesn't exist, it should solve your problem.