How to disable scrolling for UITableView header, to be always visible? (To have column titles.)
I am not sure if I am getting what you mean, are you using a UITableViewController?
If you want to have a header that is not scrollable maybe you can try to put a UIView at the top of your tableview and add sublayers to it as needed.
If a tableview with multiple fixed section headers is what you want, I would suggest using different tableviews and adding UIViews on top of each one for the header.
For handling delegate and datasource use NSObject's - (BOOL)isEqual:(id)anObject .
For example:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if ([tableView isEqual:markosFirstTableView])
{
return 1;
}
else
{
return 5;
}
}
Does this help?
Related
Is there an easy way to reload the suppplementary view only in a UICollectionViewFlowLayout? I don't want to reload the whole thing. Is it possible to do so?
After reviewing the documentation, I'm not sure about reloading an individual supplementary view, but you can use reloadSections: to update 1 or more sections in the UICollectionView. (documentation) So when a section header needs updating, you can call:
Objective-C:
[self.collectionView reloadSections:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, 3)]];
Swift:
self.collectionView?.reloadSections(IndexSet(0 ..< 3))
Which happens to call:
- (UICollectionReusableView *)collectionView: (UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
//Place logic for handling update here...
}
If you want to change the layout or size of the supplementary view from the Controller, use[self.collectionView.collectionViewLayout invalidateLayout].If you want to refresh the supplementary view only,use [supplementaryView setNeedsDisplay].Use both if the supplementary view is complex and/or will change its dimensions.
Two UITableViewCell related questions:
In my custom UITableViewCell I loop through an array (of which I do not know how many objects it holds) and add a UILabel displaying some text for each object in that array.
This means I have to adjust the height of the cell so that these labels fit in. How can I do this?
When going into edit mode, I have the cells indent, however I do not want this. I have tried the following:
cell.shouldIndentWhileEditing = NO;
and
-(BOOL)tableView:(UITableView *)tableView shouldIndentWhileEditingRowAtIndexPath:(NSIndexPath *)indexPath
{
return NO;
}
Both sadly failed, I have I no idea why. How could I possible remedy this?
Any help is much appreciated with either of these issues, thanks.
You can specify the height for every row with the delegate method [UITableViewDelegate tableView:heightForRowAtIndexPath:].
Just change what the method returns and the reload your table.
This method actually has nothing to do with the indendation of cell content:
Asks the delegate whether the background of the specified row should be indented while the table view is in editing mode.
You can try to set indentationWidth but I never managed to make it work.
Fortunately, it's easy to change everything you want in [UITableView layoutSubviews] method.
Example:
- (void)layoutSubviews {
[super layoutSubviews];
self.contentView.frame = self.bounds;
}
You may also need to set
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath;
{
return UITableViewCellEditingStyleNone;
}
For the dynamic height part there are plenty of other answers and a quick google found a tutorial here
I have a UITableView where I want to force a refresh of just a specific section header row, not the data rows. For example, refresh the header for section 3. I know how to reload an entire section (header plus data), but can just the section header be refreshed?
EDIT: When data changes in one section of the table I want to update information in the header of a DIFFERENT section. Therefore, I need to get a reference to the section header and then refresh it.
If the header is a custom UIView, then you can just call setNeedsDisplay on the UIView rather than on the UITableView.
Well, in my case, after some asynchronous task i need to update my custom section header view.
and I get it to update it's height using :
This Swift 3+ Code
//to reload your cell data
self.tableView.reloadData()
DispatchQueue.main.async {
// this is needed to update a specific tableview's headerview layout on main queue otherwise it's won't update perfectly cause reloaddata() is called
self.tableView.beginUpdates()
self.tableView.endUpdates()
}
UITableView does *not have any such method to reload only the header view/title ...You have to reload the whole section or the table.
I beg to differ. I've run into this while deleting rows with custom section headers and (at least in iOS 6) you can simply call:
[self tableView:self.tableView viewForHeaderInSection:[indexPath section]];
And as long as you have proper code to return a view in that method, you can easily refresh the header for a specific section:
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
if ([self tableView:tableView numberOfRowsInSection:section] == 0) {
return nil; //hide the header if there are no rows...
} else {
// configure or refresh the header...
}
}
I have a custom UIView subclass that i'm trying to use as a header for one of my grouped tableview sections. I save an instance of that view in the tableViewController and use that to return the height for the header section as well as the view itself. the problem is that somehow that instance variable changes from a UIView to a CALayer in the middle of a reloadData call which causes a crash, since the instance has a special method to return it's expected height. this is the code that crashes:
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
if (section == 0)
{
return [self.dataHeader frameHeight];
}
return 0.0f;
}
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
if (section == 0)
{
return self.dataHeader;
}
return nil;
}
I set a breakpoint at the first return in the if block of the heightForHeaderInSection method, and it hits it 4 times; the first three return the dataHeader successfully, while the fourth time shows it to be a CALayer and crashes with a doesNotRecognizeSelector exception (my tableview has 2 sections if that makes a difference). Is there any reason why this happens, and is there a way to stop it?
What does your initialization code for dataHeader look like? When you initialize dataHeader, are you properly retaining it?
My guess is that your dataHeader view is getting released before you intended.
The problem seems to be that you have 2 sections and somehow the app thinks there are 4. Here's how I would debug this problem:
1) What is numberOfSectionsInTableView returning (is it implemented)?
I assume that each header method should be called n times, where n is the number of sections in your table. I would also assume that the app asks the aforementioned delegate what n is.
2) What are the values of section each time these delegates are called?
There should only be one call per section, unless I'm missing something, and I would be amazed if the delegate gets called more than once with the same section value.
I am setting the row height of my UITableView using following code
[tableView setRowHeight: 100.00];
I am using the single line as separator in the UITableView.
Eventhough setting the height above, height of row does not get change.
You should implement
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
delegate method. and return 100.0 there.
You should avoid the heightForRowAtIndexPath if all your rows are of similar height and use the rowHeight property. According to the documentation:
There are performance implications to using tableView:heightForRowAtIndexPath: instead of rowHeight. Every time a table view is displayed, it calls tableView:heightForRowAtIndexPath: on the delegate for each of its rows, which can result in a significant performance problem with table views having a large number of rows (approximately 1000 or more).
In the UITableViewController subclass it could be done, for instance, in the viewDidAppear method (the UITableViewController has a reference to the tableView):
self.tableView.rowHeight = 79.f;
The row height is baked into the cells when they are first displayed.
Did you set UITableView#rowHeight before setting the data source?
If not, do so.
If for whatever reason you can't, your other option is to call UITableView#reloadData after setting the row height.
I did like this, here tableobj is nothing but UITableView object in my application.
- (void)viewDidLoad
{
[super viewDidLoad];
[tableObj setRowHeight:100.0f];
}
Or handle it in numberOfRowsInSection: like:
- (NSInteger)tableView:(UITableView *)tblView numberOfRowsInSection:(NSInteger)section {
[tableObj setRowHeight:100.0f];
return [soandso count]; // soandso is my object
}
Because set the rowHeight before setting the data source. It worked for me (for equal row heights).
The better and cleaner solution is to implement the delegate function (Maybe not the best one if your UITableView has many rows ...).
Also, think that UITableVieCell are UIView so you could change their height firstly...
Delegates are very powerful in iPhone dev, here the UITableViewDelage:
http://developer.apple.com/iphone/library/documentation/uikit/reference/UITableViewDelegate_Protocol/Reference/Reference.html
You can also change the indentForRow, displayCellForRow, heightForRow,edit stuff .....
I dont think there is such a method in UITableView...
Instead you can use the property rowHeight...
Try,
tableView.rowHeight =100;