viewForHeaderInSection autolayout - pin width

Question

I'm using the UITableView delegate method viewForHeaderInSection to provide a section header in my UITableView.

I initially create a view like this:

UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 50)];

Then add some subviews using Autolayout then return the headerView

The problem I have is I don't want to specifically specify the headerView size. I want to use Autolayout to pin left & right edges to the width of the view. Here's the problem, I have no superview to use in the Autolayout code.

Using the above code, means the header view doesn't autoresize on rotation. You must reload the tableview after rotation.

Any ideas how I can set headerView to pin it's edges to the tableview?

Thanks

Answer 1

From my testing, and this answer here, the UIView returned from that method automatically has its origin set to (0, 0), its height set to the value returned from -tableView: heightForHeaderInSection: and its width set to the width of the UITableView.

I was able to add controls to that UIView and even lay them out with auto layout without specifying any particular sizing in the init method.

Here's my code to create the header view:

self.headerView = [[UIView alloc] init];

Here's the code where I lay out the controls inside the header view:

- (void)layoutControls {
    [self.headerView addSubview:self.segmentedControl];
    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(margin)-[control]-(margin)-|"
                                                                            options:0
                                                                            metrics:@{@"margin":    @(self.segmentedControlLeftRightMargin)}
                                                                              views:@{@"control":   self.segmentedControl}]];
    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(margin)-[control(==height)]"
                                                                            options:0
                                                                            metrics:@{@"margin":    @(self.segmentedControlTopMargin),
                                                                                      @"height":    @(self.segmentedControlHeight)}
                                                                              views:@{@"control":   self.segmentedControl}]];

    [self.headerView addSubview:self.searchBar];
    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(margin)-[control]-(margin)-|"
                                                                            options:0
                                                                            metrics:@{@"margin":    @(self.searchBarLeftRightMargin)}
                                                                              views:@{@"control":   self.searchBar}]];
    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[control1]-(margin1)-[control2]-(margin2)-|"
                                                                            options:0
                                                                            metrics:@{@"margin1":   @(self.segmentedControlBottomMargin),
                                                                                      @"margin2":   @(self.searchBarBottomMargin)}
                                                                              views:@{@"control1":  self.segmentedControl,
                                                                                      @"control2":  self.searchBar}]];

}

Here are the methods for the UITableViewDelgate Protocol:

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
    // The hard-coded values are accurate for my controls, but you might need more advanced logic
    return 44.0f + self.segmentedControlBottomMargin + 44.0f + self.searchBarBottomMargin;
}
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    return self.headerView;
}