切换视图时，核心数据使属性为NULL

Question

I have four views.

View 1, shows a table view with an add button. (Add button not visible, it is above screen shot bounds)

View 2 ( presented when add button is pressed) allows the user to input data about the table view cell they would like to add. Once the save button is pressed, the new cell is added to the view.

View 3 If the user would like to edit a cell, they just tap the cell. This view Just allows the user to edit the cell that is already in the table.

But when i simply put view 4 in between view 1 (the table view) and 3 (the cell editor view), the attributes/labels show null where the user input is supposed to be shown. But when i remove view 4 from in between view 1 and 3, the app works perfect again. Any reasons?

I am simply switching views via:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Storyboard" bundle:nil];

View3 * three = (View3 *) [storyboard instantiateViewControllerWithIdentifier:@"view3VC"];

View4 * four = (View4 *) [storyboard instantiateViewControllerWithIdentifier:@"view4VC"];

[tableView deselectRowAtIndexPath:indexPath animated:YES];

three.managedObjectContext = self.context;

MyEntityClass *entity = [self.tableArray objectAtIndex:indexPath.row];

three.3entity = entity;

[self presentViewController:four animated:YES completion:nil];

}

Answer 1

It's a bit confusing but I think I would try to help you.

In your code:

MyEntityClass *entity = [self.tableArray objectAtIndex:indexPath.row];
three.3entity = entity;

You said it works when you call view3, I guess it is because you've assign the entity to the view3.

But if you present view4 like this, you didn't assign anything to it between.

View4 * four = (View4 *) [storyboard instantiateViewControllerWithIdentifier:@"view4VC"];

AND

[self presentViewController:four animated:YES completion:nil];

Now view4 is a totally fresh and empty view controller. It's not strange that it shows null in your labels.

Try fix it in the way exactly as view3.