使用情节提要板无法正确显示Subview-title

Question

I have a tableview and a detailview, connected with segues. I want the detailview's title to be the title of the selected cell.

If I use this code in GradeDetail.m , it works, but is static, of course:

self.navigationController.title = @"Title goes here";

If I use this on the other hand, it doesn't work, but should be dynamic:

self.navigationItem.title = grade.fag;

I have the class Grade imported where necessary and "fag" (means "school subject" in Danish, not gay) property defined in the class.

Here is an excerpt of the code from the tableview:

...
- (id)initWithCoder:(NSCoder *)aDecoder
{
if ((self = [super initWithCoder:aDecoder])) 
{
    grades = [[NSMutableArray alloc] init];

    Grade* grade = [[Grade alloc] init];
    grade.fag = @"Dansk";
    grade.mundtlig = @"7";
    [grades addObject:grade];

...    

}
return self;
}

And the code pushing the detail-view:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath     *)indexPath
{    
 GradeDetail *detailViewController = [[GradeDetail alloc] init];

Grade* grade = [self.grades objectAtIndex:indexPath.row];
detailViewController.grade = grade;

//[self.navigationController pushViewController:detailViewController animated:YES];
}

Notice from the above code, what I commented out:

[self.navigationController pushViewController:detailViewController animated:YES];

If I remove the segue in the storyboard, and use this line of code instead, the detail-view shows the correct title, but the view isn't loading correctly. (Read: I don't want to use this line of code, I want it to work in storyboard.)

Please tell me if you want to see more of the code or have some of the above clarified.

Answer 1

You'll need to override -prepareForSegue:sender: to get a hook into the incoming view controller and set any properties required. You'll also need to specify segue identifiers in the storyboard.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"ShowGradeDetails"])
    {
        GradeDetail *detailViewController = (GradeDetail *)segue.destinationViewController;
        NSIndexPath *selectedIndexPath = [self.tableView indexPathForSelectedRow];
        Grade *selectedGrade = [self.grades objectAtIndex:selectedIndexPath.row];
        detailViewController.grade = selectedGrade;
    }
}

Answer 2

也许尝试设置viewController的标题： self.title = grade.fag;