Just a quick question about SPTrack and SPAlbum
Say I have an array of SPTracks stored in myTracks
I can get the name of this track by doing
[[myTracks objectAtIndex:0] name];
However; when I try to get the name of the album like this
[myTracks objectAtIndex:0] album];
an SPAlbum object is returned. This makes sense, but I am unable to access the name property of the SPAlbum like so:
[[[myTracks objectAtIndex:0] album] name];
The name property is defined as an NSString in SPAlbum.m. Am I attempting to access this incorrectly? Thanks for your help.
Are you getting nil back?
If so, you need to make sure your objects are loaded first, using SPAsyncLoading.
[SPAsyncLoading waitUntilLoaded:[[myTracks objectAtIndex:0] album] timeout:kSPAsyncLoadingDefaultTimeout then:^(NSArray *loadedItems, NSArray *notLoadedItems) {
if (loadItems.count == 0) return; // Album didn't load!
NSLog(#"%#", [[[myTracks objectAtIndex:0] album] name]);
}];
Related
I am currently working on an app that will use the data returned by reversegeocode. Right now I can successfully receive the following values for a location: address, city, state, zip code, and country. In addition to the values that I am able to get, I would also like to obtain the name of the neighborhood for the locations that I reversegeocode. My code is as follows:
CLLocationManager *location = [[CLLocation alloc] init];
[location setDelegate:self];
location.desiredAccuracy=kCLLocationAccuracyBest;
location.distanceFilter=kCLDistanceFilterNone;
[location startMonitoringSignificantLocationChanges];
CLGeocoder *geolocation = [[CLGeocoder alloc] init];
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
NSLog(#"Update method is definitely being called!");
NSLog(#"Your current location is : %#", [locations lastObject]);
[geolocation reverseGeocodeLocation:[locations lastObject] completionHandler:^(NSArray *placemarks, NSError *error) {
NSLog(#"Reverse geocode complete: %#", placemarks);
CLPlacemark *placemark = [placemarks objectAtIndex:0];
NSLog(#"The locality area is: %#", placemark.locality);
}];
}
I expected placemark.locality to return the neighborhood but it returns the city instead.
Any help would be greatly appreciated,
Dave
After reading the documentation Apple has for the CLPlacemark class, I noticed that there were a few fields that I was unaware of.
Inclusive in these fields is exactly what I was trying acquire, the subLocality, which seems to be Apple documentation for neighborhood. If I had just read the documentation instead of assuming the object returned from [placemarks objectAtIndex:0], when stored in CLPlacemark *placemark, would have no more data than what is shown when NSLog(#"%#", [placemarks objectAtIndex:0]) is called, I would have figured this out much sooner. Oh well. The code I used to access the neighborhood is:
[placemark subLocality];
I have a pretty weird problem. I'm using coredata to save notes. I can access/save/edit all the attributes of the "Notes" entity, besides one : category.
-(void)editCategory {
NSFetchRequest *request = [[NSFetchRequest alloc]init];
NSEntityDescription *categRequest = [NSEntityDescription entityForName:#"Notes" inManagedObjectContext:_managedObjectContext];
request.predicate = [NSPredicate predicateWithFormat:#"text = %#", noteToEdit];
[request setEntity:categRequest];
//Error handling
NSError *error = nil;
NSMutableArray *mutableFetchResults = [[_managedObjectContext executeFetchRequest:request error:&error]mutableCopy];
if (mutableFetchResults == nil) {
NSLog(#"Error happened : %#", error);
}
Notes *editMe = [mutableFetchResults objectAtIndex:0];
[editMe setCategory:editCategoryText];
NSLog(#"Category from pickerview : %#", editCategoryText);
if (![_managedObjectContext save:&error]) {
NSLog(#"couldnt save : %#", error);
}
}
This line :
[editMe setCategory:editCategoryText];
is crashing. editCategoryText is a string, as the category attribute. The weird thing is that I'm using the exact same piece of code to change the title attribute, and I don't have any problem.
Log file :
2013-11-07 15:49:20.286 Simple Notes 1[16511:a0b] -[__NSCFString managedObjectContext]: unrecognized selector sent to instance 0x8dccc30
2013-11-07 15:49:20.293 Simple Notes 1[16511:a0b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString managedObjectContext]: unrecognized selector sent to instance 0x8dccc30'
Do you have any idea why this attribute is behaving differently from the others ? Thank you.
Not at a computer so can't test this but:
Get rid of the mutableCopy. executeFetchRequest returns autoreleased objects, which you are then trying to copy, this turns into a garbage pointer, which happens to end up pointing to a string.
Actually it seems like it was a core data bug, I solved it by deleting my app in the simulator, deleting the core data model in xcode, built it again and performed a clean.
Setup: I have a collection of parent objects, call them ObjectA. Each ObjectA has a one-to-many relation to ObjectB. So, one ObjectA may contain 0..n ObjectB-s, and each ObjectB has a specific ObjectA as its parent.
Now, I would like to do a Core Data fetch of ObjectA-s, where they are sorted by their latest ObjectB. Is it possible to create a sort descriptor for that?
There is a related question that describes exactly the same situation. The answer suggests denormalizing the attribute from ObjectB into ObjectA. This would be OK if there really is no way to do this with one fetch request.
The related question also mentions:
Actually, I just had an idea! Maybe I can sort Conversations by messages.#max.sortedDate…
I tried. It doesn’t seem to be possible. I get this error:
2012-10-05 17:51:42.813 xxx[6398:c07] *** Terminating app due to uncaught
exception 'NSInvalidArgumentException', reason: 'Keypath containing
KVC aggregate where there shouldn't be one; failed to handle
ObjectB.#max.creationTime'
Is denormalizing the attribute into ObjectA the only/best solution?
You could add an attribute in ObjectB which is the time stamp of the add date, then in the fetch request you can do something like this:
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:#"objectB.addTime" ascending:YES];
...
fetchRequest.sortDescriptors = #[descriptor];
I know this question is a bit old but what I did was get all ObjectBs, iterate over the results and pull out the ObjectB property and add it to a new array.
NSFetchRequest *fetchRequest = [NSFetchRequest new];
[fetchRequest setEntity:self.entityDescForObjectB];
// sort
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"date" ascending:YES];
[fetchRequest setSortDescriptors:#[sortDescriptor]];
NSError *error = nil;
NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
NSLog(#"Error fetching objects: %#", error.localizedDescription);
return;
}
// pull out all the ObjectA objects
NSMutableArray *tmp = [#[] mutableCopy];
for (ObjectB *obj in fetchedObjects) {
if ([tmp containsObject:obj.objectA]) {
continue;
}
[tmp addObject:obj.objectA];
}
This works because CoreData is an object graph so you can work backwards. The loop at the end basically checks to see if the tmp array already has a specific ObjectA instance and if not adds it to the array.
It's important that you sort the ObjectBs otherwise this exercise is pointless.
I am wanting to set up a basic relationship with two entities in Core Data, but the relationship is either not saving, or is not working properly and I'm not sure why.
The two entities are Character and Avatar, its a one-to-one relationship. A character can have 1 avatar. Technically, it should be a "one avatar can be owned by many characters", but I'll deal with that later.
I want to add characters and assign them an avatar.
There are already 10 avatars in Core Data and 1 character, both of which I've verified via the Terminal and SQLite.
The problem is, I'm having troubling "finding an avatar by a name and then saving the relationship to a character".
So far,
I set up a fetch request called: "frqAvatarWithName" where the Predicate has the following structure:
[quote]
name == $AVATAR_NAME
[/quote]
This is so: I can find an avatar with a certain name; and then I can create a relationship with a character.
Issue 1: It gets to execute the query but then never displays how many records there are.
I get a EXC_BAD_ACCESS error in debug mode and I have traced it back to the fetch request template handling -- so, this must be in error or I have done it wrong.
Issue 2: I am not sure if I am even setting up this "basic" relationship up properly.
[code]
// This code is meant to find an avatar with a certain name and then save the relationship
// between a character and said avatar.
// This is my app delegate file for the moment
// All the files are present, and I have deleted/recreated the app various times
-(void)characterMaker
{
NSLog(#"Inside characterMaker...");
NSError *error = nil;
NSManagedObjectContext *context = [self managedObjectContext];
NSManagedObjectModel *model = [self managedObjectModel];
// Find an avatar with a specific name
NSString *nameToFind = #"avt_player_1";
// Use a Fetch request template
NSDictionary *subs = [NSDictionary dictionaryWithObjectsAndKeys:nameToFind, #"AVATAR_NAME", nil];
NSFetchRequest *fetchRequest = [model fetchRequestFromTemplateWithName:#"frqAvatarWithName"
substitutionVariables:subs];
// Set the entity to use
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Avatar"
inManagedObjectContext:context];
[fetchRequest setEntity:entity];
// Execute the query (it never even reaches this point)
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
// Handle the error
NSLog(#"Error -- %#", [error localizedDescription]);
abort();
}
NSLog(#"Found %# records", [fetchedObjects count]);
// Print out avatar names
for (Avatar *a in fetchedObjects)
{
NSLog(#"Name = %#", [a valueForKey:#"name"]);
}
// This is where I would use `a` and store it in a character entity, and thus create the relationship
[/code]
I gave up on this and did the whole project with the FMDatabase project and SQLite; I've been able to resolve the problem this way.
Thread closed.
Not sure if this is the right place (I am sure someone will let me know if it is not) I have a iPhone application that has a UITableview that is backed by core data. I want to perform a reducing search so that only the items starting with the characters entered into the search bar are shown. This is normally done with the delegate - (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText no problem. I am a little confused as I am new to Core Data how to do this. One of the big problems as I see it is going to be updating the interface to let it know what to present. I assume an alternative NSFetchedResultsController needs to be sent to the UITableView is that correct?
So here are my issues:
1) I assume I need to create a NSFetchedResultsController with only the correct items in it then tell the UITableView to use this as the dataSource and reload the table?
2) is there a better way than executing a full sorted fetch and removing those objects that do not conform. ie is there a way of doing a select where type fetch?
Thanks in advance and sorry if this is a dumb question.
Regards
Damien
Yes, you will need a new NSFetchedResultsController.
You should use a NSPredicate in your new NSFetchRequest to filter by your search text.
For example, if your managed objects have a field "name" that should be filtered:
NSPredicate *pred = [NSPredicate predicateWithFormat:#"%K beginswith[c] %#", #"name", searchText];
[fetchRequest setPredicate:pred];
I used a slightly different solution: instead of relying on a different NSFetchedResultsController, I created a NSMutableArray (filteredListContent) in my table view controller, used to store the temporary data, as inspired by Apple sample code and Mugunth Kumar's tutorial.
In tableView:cellForRowAtIndexPath:, returning the appropriate data-source array:
if(receivedTableView == self.searchDisplayController.searchResultsTableView){
Objects* object = [self.filteredListContent objectAtIndex:indexPath.row];
cell.textLabel.text = object.name;
} else {
Objects* object = [self.unfilteredListContent objectAtIndex:indexPath.row];
cell.textLabel.text = object.name;
}
As in Apple's sample code, add pretty much the same method in other methods, such as
- (NSInteger)tableView:(UITableView *)receivedTableView numberOfRowsInSection:(NSInteger)section {
if(receivedTableView == self.searchDisplayController.searchResultsTableView){
return [self.filteredListContent count];
}
return [self.unfilteredListContent count];
}
As well as in tableView:didSelectRowAtIndexPath:...
Then conformed to UISearchDisplayDelegate protocol and added the following methods:
- (void)filterContentForSearchText:(NSString*)searchText
{
if (!self.filteredListContent) {
self.filteredListContent = self.filteredListContent = [[NSMutableArray alloc] init];
}
[self.filteredListContent removeAllObjects];
for (Objects *object in [self.coreDataStuffVariable.fetchedResultsController fetchedObjects])
{
NSPredicate *predicate = [NSPredicate predicateWithFormat:
#"(SELF contains[cd] %#)", searchText];
NSString * elementTitle = [NSString stringWithFormat:#"%#", object.name];
[elementTitle compare:searchText options:NSCaseInsensitiveSearch];
if([predicate evaluateWithObject:elementTitle])
{
[self.filteredListContent addObject:password];
}
}
}
- (BOOL)searchDisplayController:(UISearchDisplayController *)controller
shouldReloadTableForSearchString:(NSString *)searchString{
[self filterContentForSearchText:searchString];
// Return YES to cause the search result table view to be reloaded.
return YES;
}
Pretty simple. I guess it can end up badly if the core data objects are reloaded during a search, but well... if you can sleep knowing that then it may be a good solution!