xcode, reloading table view on exiting seque

问题

I'm trying to reload the values of a table view after exiting from a seque. The process being: I perform the seque manually from the profile selection view, add a new profile name, return to the profile selection view. Then I would like to reload the table view adding the new profile name. It is running the code fine (same code as original entry into the scene), but I can't seem to get the native methods of numberOfRowsInSection and numberOfRowsInSection to repopulate the table view. I actually have to leave the screen and reenter it before the new profile name will update. Any thoughts?

//** performing seque manually

-(IBAction)buttonAddNewProfile:(id)sender
{
    // creating object for profile selection screen
    UIStoryboard *ProfileSelectionStoryboard=[UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];

    // creating object for add new profile storyboard
    AddNewProfileViewController *addnewprofileVC=[ProfileSelectionStoryboard instantiateViewControllerWithIdentifier:@"Add New Profile"];

    // setting the transition style
    addnewprofileVC.modalTransitionStyle=UIModalTransitionStylePartialCurl;

    // performing the segue
    [self presentViewController:addnewprofileVC animated:YES completion:nil];

    // performing new table view load on return from new profile
    [self loadUsers];
}

//** function to load the new profile names in.

-(void)loadUsers
{
    // retreiving the users from the database
    SQLiteFunctions *sql = [[SQLiteFunctions alloc] init];

    // testing for successful open
    if([sql openDatabase:@"users"])
    {
        // setting query statement
        const char *query = "SELECT * FROM  users;";

        // testing for that profile name existing already
        if([sql getUserRecords:query] > 0)
        {
            // initializing array
            NSMutableArray *names = [[NSMutableArray alloc] init];

            // loop through object compling an array of user names
            for(Users *ProfileUser in sql.returnData)
            {
                // adding user name to the listview array
                [names addObject:ProfileUser.user_name];
            }

            // setting table view array to local array
            tableData = names;
        }
    }
}

//** methods to reload the table view

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section;
{
    // returning the number of rows in the table
    return [tableData count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath;
{
    // setting up the table view cells for data population
    UITableViewCell *cell = nil;
    cell = [tableView dequeueReusableCellWithIdentifier:@"MyCell"];

    // testing for cell parameters
    if (cell == nil)
    {
        // setting up cloned cell parameters
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"MyCell"];
    }

    // setting cell values to the array row value
    cell.textLabel.text = [tableData objectAtIndex:indexPath.row];

    // returning the current row label value
    return cell;
}

回答1:

You have a few different options here:

1) The easiest is to simply reload the table every time that the view controller is about to display its view:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self.tableView reloadData];
}

The downside though, is that this will be executed every time that the view is displayed, even when you don't necessarily need to reload the data.

2) If you are using storyboard's and targeting iOS 6+ then you can use an unwind segue to call a specific method on your view controller when going back from the add profile view controller. For more info, see this SO question/answers: Does anyone know what the new Exit icon is used for when editing storyboards using Xcode 4.5?

3) If you are targeting older versions of iOS or aren't using storyboards, then you can create a protocol with a method that should be called whenever a new profile is added and you can reload the data whenever that method is called. There are lots of questions here on SO which cover how to do this (like dismissModalViewController AND pass data back which shows how to pass data, but you can do the same thing to just call a method).

回答2:

This the actual answer from lnafzinger in the comments above. Thanks again.

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self.tableView reloadData];
}

It took me a bit to figure this out, but it is because you are using the UIModalTransitionStylePartialCurl modalTransitionStyle. I guess they don't call it because it doesn't completely leave the screen. If you use a different style (like the default) then it will call viewWillAppear. If you want to stay with that, then you should probably use one of the other methods. – lnafziger

来源：https://stackoverflow.com/questions/14030901/xcode-reloading-table-view-on-exiting-seque

标签

xcode

tableview

segue