排序核心数据UITableview

Question

I am trying to sort a tableview based on the value of a core data attribute (name) this is the code I have so far but it does not seem to do anything?

- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];

// Fetch the devices from persistent data store
NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Device"];
self.devices = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

[NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];


[self.tableView reloadData];
}

Thanks for any help.

Answer 1

Try to modify your code like this :

    - (void)viewDidAppear:(BOOL)animated
    {
    [super viewDidAppear:animated];

    // Fetch the devices from persistent data store
    NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Device"];


    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:NO];
    NSArray *sortDescriptors         = [[NSArray alloc] initWithObjects:sortDescriptor, nil];


    // Set descriptors
    [fetchRequest setSortDescriptors:sortDescriptors];

    self.devices = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

    [self.tableView reloadData];
}

You need to set the sort descriptor to your fetchrequest. Supposing the entity "Device" has an attribute "name"