CODEWITHSUNDEEP
iphoneiosuitableview
htafoya
htafoya

Reputation: 19283

uitableview headerViewForSection: always returns nil

I have a table with custom header views that no matter when, or what value I choose for section, I always get nil value. I have another table with the same problem.

I can see the header views if I print the value of [tableview subviews], but I don't know why the method won't return anything.

What I am trying to do is to get an activityIndicator that is in the headerview and start it or stop it with a method call.

The headers are always painted ok, but I can't get a reference back to it. Also, calling headerViewForSection: doesn't call the delegate method, is that normal?

footerViewForSection: has the same problem

Some code:

- (UIView*) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {

    NSArray* objs = [[NSBundle mainBundle] loadNibNamed:@"iPadTableCells" owner:nil options:nil];
    UIView* header = [objs objectAtIndex: 0];

    UIActivityIndicatorView* activityIndicator = (UIActivityIndicatorView*) [header viewWithTag:5];
    [activityIndicator startAnimating]

    return header;

}

from any method:

    UIView* headerView = [tableview headerViewForSection: section];  //returns nil

    if (headerView) {
        UIActivityIndicatorView* activityIndicator = (UIActivityIndicatorView*)[headerView viewWithTag: 5];
        [activityIndicator stopAnimating];
    }

Upvotes: 19

Views: 16118

Answers (3)

Aaron Brager
Aaron Brager

Reputation: 66302

Answer

From the docs:

To make the table view aware of your header or footer view, you need to register it. You do this using the registerNib:forHeaderFooterViewReuseIdentifier: or registerClass:forHeaderFooterViewReuseIdentifier: method of UITableView.

(The Swift equivalent is register(_:forHeaderFooterViewReuseIdentifier:).)

So you need to register the nib, and then get it using a reuse identifier, instead of pulling it straight out of the app bundle, which is what you're doing now.

...if you want to use the headerViewForSection method.

Alternate Answer

Alternatively, you could check whether to keep spinning inside the viewForHeaderInSection method and then send just call:

[self.tableView beginUpdates];
[self.tableView endUpdates];

To refresh the section header.

(Note that this alternative approach will destroy and recreate your whole view, so if you have a big table with lots of data, it may not be very efficient.)

Upvotes: 18

Kesong Xie
Kesong Xie

Reputation: 1396

In swift

All you need is to create an instance of UITableViewHeaderFooterView for the header view you need to return

 func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        let sectionHeaderView = UITableViewHeaderFooterView()
        //customize your view here
        return sectionHeaderView
    }

Upvotes: 5

staticVoidMan
staticVoidMan

Reputation: 20274

It's been awhile since this question was asked and recently I had come across a similar issue and had asked my own question here: UITableView -headerViewForSection returns (null)
I believe I have the answer.

Prerequisite Steps:

  1. Create a UITableViewHeaderFooterView subclass and name it CustomHeaderView
  2. Create a view interface nib file for the class (apparently you have named it iPadTableCells here)
  3. In the xib, select the View & in it's Identity Inspector
    • Specify the Custom Class as CustomHeaderView
  4. Make a property, synthesize and connect it to the xib
    • @property (strong, nonatomic) IBOutlet UIActivityIndicatorView *activityIndicator;

Use the following code:

- (UIView*) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    static NSString *HeaderIdentifier = @"header";
    CustomHeaderView *header = [tableView dequeueReusableHeaderFooterViewWithIdentifier:HeaderIdentifier];

    if(!header) {
        NSArray* objs = [[NSBundle mainBundle] loadNibNamed:@"iPadTableCells"
                                                      owner:nil
                                                    options:nil];
        header = [objs objectAtIndex: 0];
    }

    [header.activityIndicator startAnimating];
    return header;
}

then you can access it this way: 

CustomHeaderView *headerView = (CustomHeaderView*)[tableView headerViewForSection:section];
[headerView.activityIndicator stopAnimating];

Upvotes: 9

Related Questions