Asked  10 Months ago    Answers:  5   Viewed   188 times

i have a UITableView, that displays expenses from a current month (see screenshot):

My problem is with the header for empty sections. is there any way to hide them? The data is loaded from coredata.

this is the code that generates the header title:

TitleForHeader

-(NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{
if ([tableView.dataSource tableView:tableView numberOfRowsInSection:section] == 0) {
    return nil;
} else {

NSDate *today = [NSDate date ];
int todayInt = [dataHandler getDayNumber:today].intValue;

NSDate *date = [NSDate dateWithTimeIntervalSinceNow:(-(todayInt-section-1)*60*60*24)];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:[[NSLocale preferredLanguages] objectAtIndex:0]]];    
[dateFormatter setTimeStyle:NSDateFormatterNoStyle];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
NSString *formattedDateString = [dateFormatter stringFromDate:date];
    return formattedDateString;}

}

ViewForHeader

-(UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section{
if ([tableView.dataSource tableView:tableView numberOfRowsInSection:section] == 0) {
    return nil;
} else {

    UIView *headerView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 312, 30)];
    UILabel *title = [[UILabel alloc]initWithFrame:CGRectMake(4, 9, 312, 20)];
    UIView *top = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 312, 5)];
    UIView *bottom = [[UIView alloc]initWithFrame:CGRectMake(0, 5, 312, 1)];

    [top setBackgroundColor:[UIColor lightGrayColor]];
    [bottom setBackgroundColor:[UIColor lightGrayColor]];

    [title setText:[expenseTable.dataSource tableView:tableView titleForHeaderInSection:section]];
    [title setTextColor:[UIColor darkGrayColor]];
    UIFont *fontName = [UIFont fontWithName:@"Cochin-Bold" size:15.0];
    [title setFont:fontName];


    [headerView addSubview:title];
    [headerView addSubview:top];
    [headerView addSubview:bottom];

    return headerView;

}

}

heightForHeader

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {

NSLog(@"Height: %d",[tableView.dataSource tableView:tableView numberOfRowsInSection:section] == 0);
if ([tableView.dataSource tableView:tableView numberOfRowsInSection:section == 0]) {
    return 0;
} else {
    return 30;
}
}

numberOfRowsInSection

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
 {

int rows = 0;
for (Expense* exp in [dataHandler allMonthExpenses]) {
    if ([exp day].intValue == section) {
        rows++;
    }
}

return rows;
}

sebastian

 Answers

5

What if in – tableView:viewForHeaderInSection: you return nil if the section count is 0.

EDIT : You can use numberOfRowsInSection for obtaining the number of elements in the section.

EDIT: Probably you should return nil also in titleForHeaderInSection if numberOfRowsInSection is 0.

EDIT: Did you implement the following method?

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

EDIT : Swift 3 example

override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
    switch section {
    case 0:
        if self.tableView(tableView, numberOfRowsInSection: section) > 0 {
            return "Title example for section 1"
        }
    case 1:
        if self.tableView(tableView, numberOfRowsInSection: section) > 0 {
            return "Title example for section 2"
        }
    default:
        return nil // when return nil no header will be shown
    }
    return nil
}
Saturday, July 31, 2021
 
Lance
 
3

It looks like what it happening is that internally Apple's UITableView code is assuming that when you delete a row, the first section of your view will get shorter. By making the section header footer suddenly get taller to compensate for the last row, you appear to be confusing it.

Two ideas for you to try:

1. try making the optional section footer a pixel or two smaller than the table cell that's going away, so that the animation code gets to do a pixel or two of animation

2. instead of deleting the only row of your table, when there are no "real" data rows let the table still have numberOfRowsInSection return 1 and make a fake "no data" cell rather than using a table footer for the "no data" case.

This is one of those cases where you just have to accept that Apple has written half of your program for you and you have to conform to some choices your co-author has made, whether you like them or not.

Friday, July 30, 2021
 
Maury
 
4

Just having a quick look at your code - you seem to be pushing blocks onto asynchronous queues, but you are calling UI code in those blocks.

You should only run UI code on the main thread.

As for a solution - have a look at some of the open source implementations to either give you an idea of what you should be doing, or just use them directly.

One such is AsyncImageView on Github.

There are others that a quick search will bring up.

Saturday, August 7, 2021
 
Anax
 
1

You sure you are using UITableViewStyleGrouped style?

Because by default it is set to UITableViewStylePlain which shows empty cells too after displaying filled cells.

Friday, September 3, 2021
 
xilec
 
2

You can send NSNotification after

pressing done button on second tab

and handle this notification on first tab controller.

Saturday, October 16, 2021
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