Question

I have a database with 10 tables. As I need to access this database in different view controllers, I have to declare the two methods shown below in each of them. Is there a way I can avoid this by declaring these methods in the application delegate. If yes, how can I go about using these methods in different classes.

- (NSString *) getWritableDBPath {

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES);
    NSString *documentsDir = [paths objectAtIndex:0];
    return [documentsDir stringByAppendingPathComponent:DATABASE_NAME];
}

-(void)createEditableCopyOfDatabaseIfNeeded 
{
    // Testing for existence
    BOOL success;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                         NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:DATABASE_NAME];
    NSLog(@"%@",writableDBPath);

    success = [fileManager fileExistsAtPath:writableDBPath];
    if (success)
        return;

    // The writable database does not exist, so copy the default to
    // the appropriate location.
    NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath]
                               stringByAppendingPathComponent:DATABASE_NAME];
    success = [fileManager copyItemAtPath:defaultDBPath
                                   toPath:writableDBPath
                                    error:&error];
    if(!success)
    {
        NSAssert1(0,@"Failed to create writable database file with Message : '%@'.",
                  [error localizedDescription]);
    }
}

Answer 1

in your view controller first of all create a delegate variable

YourAppDelegate *appDelegate=(YourAppDelegate *)[[UIApplication sharedApplication]delegate];

then u can call any methods that you have define in your delegate
like [appDelegate methodName];