Error says source path is nil - ios

Question

I am quite new to iOS app development.
I am trying to build a sample DB app which saves records to DB and fetches from it.
The App works well when I test with simulators. I have created a local database and also I am programatically making a copy of it when required. Also I have checked that local DB is referenced in the 'Copy Bundle Resources'.
But the error I am getting is, " * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[NSFileManager copyItemAtPath:toPath:error:]: source path is nil' ".
I think the piece of code which causes this problem is
" [FileManager copyItemAtPath:databasePathFromApp toPath:DBPath error:nil]; "
It work perfectly good for simulators but not when I test with my device.
Expecting help.
My code is,
- (id)init {
self = [super init];
//Datbase Name
DBName=#"Person.sqlite3";
//Getting DB Path
NSArray *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDir = [documentsPath objectAtIndex:0];
DBPath=[documentsDir stringByAppendingPathComponent:DBName ];
//DBPath = [[NSString alloc] initWithString: [documentsDir stringByAppendingPathComponent:DBName]];
NSLog(#"DBPath is %#",DBPath);
return self;
}
-(void)checkAndCreateDB{
BOOL Success;
//NSFileManager maintains File
NSFileManager *FileManager = [NSFileManager defaultManager];
NSLog(#"line 1");
//Checks Database Path
Success = [FileManager fileExistsAtPath:DBPath];
NSLog(#"line 2");
//If file exists, it returns true
if(Success)return;
NSLog(#"line 3");
//NSString *databasePathFromApp = [[[NSBundle mainBundle]resourcePath]stringByAppendingPathComponent:DBName];
// Get the path to the database in the application package
NSString *databasePathFromApp=[[NSBundle mainBundle] pathForResource:#"Person.sqlite3" ofType:#"sqlite3"];
NSLog(#"line 4");
[FileManager copyItemAtPath:databasePathFromApp toPath:DBPath error:nil];
//[FileManager release];
NSLog(#"line 5");
}
My Application crashes while testing in device after the line NSLOG(line 4); But works good in simulator.
Many Thanks
Prakash

Answer 1

The device can not write to the app bundle, you need to use the Documents directory.
Here is how to get the Documents directory path:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingPathComponent:fileName];
If you have an initial db in the app bundle copy it to the Documents on initial startup.

Answer 2

change this line
NSString *databasePathFromApp=[[NSBundle mainBundle] pathForResource:#"Person.sqlite3" ofType:#"sqlite3"];
to
NSString *databasePathFromApp=[[NSBundle mainBundle] pathForResource:#"Person" ofType:#"sqlite3"];
also, pay attention to capitalisation, iOS devices are case sensitive, while on simulator, you'll get away with wrong capitalisation