In one section of my app I have a UITableView which is working fine right now. I would like to set row 0 cell.textLabel.text to #"Some string". Once row 0 has been set I would then like to load the rest of the rows from an array. Currently on load my array populates the table view but I'm trying to set row 0 as a sticky. The closest example I can think of is a forum topic that is set to stay at the top. My array is constructed of returned data from a web service call.
It's been a while since I've messed with table views, and I'm having a blank on this one.
The table view is 1 section, and I get the rows by counting the elements in the array. Since I would like to create an additional cell (row 0) I would call [array count] + 1. I don't know if this approach is the best one which is why I'm reaching out to the community here.
Any insight or a shove in the right direction would be great at this point.
You're on the right track:
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [array count]+1;
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
if ([indexPath row] == 0) {
// Code for first
[[cell textLabel] setText:#"First cell"];
} else {
[[cell textLabel] setText:[array objectAtIndex:[indexPath row]-1]];
}
return cell;
}
If you want the top of your table to be "sticky", why not consider using that string as a section header or title? In this case, the header stays visible at all times until the next section (e.g. if you had two sections, that is) is fully on the screen.
In any event, in one of my current projects I'm required to do roughly the same thing that you're doing and I have a static string being returned in row 0 (which scrolls off the top of screen when the table view scrolls down).
And in my UITableViewDataSource method, I always add one for the static cell to the number of objects in my array and in my "cellForRowAtIndexPath:" method, I increment the row by one when the indexPath.row is not zero. And if it is zero, I return my static string.
And dark_knight provides some nice sample code that illustrates what I was describing to you. So +1 to him/her.
Related
I have 6 sections in a UItableView, every section displays 2 cells, normally, I want it like this:
However, here is what I have:
Every indexPath.row is duplicated in every section.
Here is the code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"avenir";
Avenir *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(!cell) {
cell =[[Avenir alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
cell.equipea.text=[arrayofClubA objectAtIndex:indexPath.section];
cell.equipeb.text=[arrayofClubB objectAtIndex:indexPath.section ];
return cell;
}
The elements are retrieved from two NSMutableArrays, one for the first left element in cell and the other for the right element cell.
What is wrong?
Thank you for helping.
You need to calculate the correct index from both the row and the column. Since you have two pairs of rows per section, you need to multiply section by two, and add row, which will be either zero or one. The end result should look like this:
NSUinteger pos = indexPath.section*2 + indexPath.row;
cell.equipea.text=[arrayofClubA objectAtIndex:pos];
cell.equipeb.text=[arrayofClubB objectAtIndex:pos];
You're always fetching the identical text for each section, since
cell.equipea.text=[arrayofClubA objectAtIndex:indexPath.section];
always returns the same value for each section (since indexPath.section contains the section's index). Perhaps you wanted to do to the following instead?
cell.equipea.text=[arrayofClubA objectAtIndex:indexPath.row];
Also, for these kind of uses, it might be a lot more straight forward to use the free Sensible TableView framework as it automatically handles displaying your arrays.
I have implemented an iPhone app that uses UITableViewController/UITableView and Core Data. Further, I use a NSFetchedResultsController to manage the table data. This was all very straight forward and works great. I then decided that I should display a message in the UITableView when no rows where found/retrieved. After researching this, it appeared that the best way (perhaps the only way) to do this was to return a "dummy" cell that contains the message. However, when I do this, I get a nastygram from the runtime system that complains (and rightfully so) about data inconsistencies: "Invalid update: invalid number of sections. The number of sections contained in the table view ...". Here is the relevant code:
- (NSInteger) numberOfSectionsInTableView: (UITableView *)tableView
{
if ([[self.fetchedResultsController fetchedObjects] count] == 0) return 1;
return [[self.fetchedResultsController sections] count];
}
- (NSInteger) tableView: (UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if ([[self.fetchedResultsController fetchedObjects] count] == 0) return 1;
id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex: section];
return [sectionInfo numberOfObjects];
}
- (UITableViewCell *) tableView: (UITableView *)tableView cellForRowAtIndexPath: (NSIndexPath *)indexPath
{
if ([[self.fetchedResultsController fetchedObjects] count] == 0) {
UITableViewCell *cell = [[UITableViewCell alloc] init];
cell.textLabel.text = #"No widgets found.";
return cell;
}
STCellView *cell = (STCellView *)[tableView dequeueReusableCellWithIdentifier: #"ShieldCell"];
[self configureCell: cell atIndexPath: indexPath];
return cell;
}
I have read responses from similar questions and it appears that I should use
insertRowsAtIndexPaths: withRowAnimation:
to insert the "dummy" message row into my table. However, this also means removing the "dummy" row when a real row is inserted. I can do this, but it seems like there should be an easier way to accomplish this. All I want to do, is to display a message indicating that there are no rows in the table (simple enough?). So, my question is this: Is there a way to display a message in an UITableView without using the "dummy" cell approach OR is there a way to convince UITableViewController/NSFetchResulsController that this is only a "dummy" row and they should not get so upset about it because it is not a real row (from my point of view) in the table?
Any help you can provide would be very appreciated (I am a struggling newbie to iPhone development and I want to learn the best practices). Thanks.
Rather than hack with the tableview datasource to get the intended UI you should add the "No rows found" message to the tableview header instead.
I did as follows in viewDidLoad.
UILabel *label = [[UILabel alloc] init];
[label setTextColor:[UIColor lightGrayColor]];
[label setText:#"No widgets found."];
[label sizeToFit];
label.frame = CGRectMake((self.tableView.bounds.size.width - label.bounds.size.width) / 2.0f,
(self.tableView.rowHeight - label.bounds.size.height) / 2.0f,
label.bounds.size.width,
label.bounds.size.height);
[self.tableView insertSubview:label atIndex:0];
In this case, each TableViewCells must be opaque to hide the label. or need to toggle the hidden property of the label according to the row count.
An alternative approach, which I have used before is to use Core Data to manage the update for you by inserting a 'no rows' entity for the section where no rows have been detected in your model class, which handles the data update.
There are a number of ways to implement this e.g. set the name/title field to a known status message or a flag within the entity. Once inserted you can detect the 'no rows' entity in the cellForRowAtIndexPath delegate method and insert an alternative table cell to show the message.
Just remove the 'no rows' entity before refreshing the data for that section.
My simple suggestion to display an empty message is to rearrange your controller to be a simple UIViewController (not a UITableViewController).
This UIViewController is composed by a UITableView (the controller is the data source and the delegate for your table) and by a UILabel (or a UIView that contains a UILabel) that displays the empty row message.
In this manner you can control the visibility of the table and the label based on the retrieved rows.
This approach could be laborious but I think it's good to avoid hacking NSFetchResultsController and data source. Furthermore you could have a complete control on arranging the position for your empty message.
As #Rog suggested you could also use the table view header to display that message. As you prefer.
Hope it helps.
I want my tableView to show 6 rows with text in it, in this case "Example." As far as I can tell, I have my numberOfSectionsInTableView: and numberOfRowsInSection: set properly. See example code below:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
// Return the number of rows in the section.
return 6;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
cell.textLabel.text = #"Example";
return cell;
}
The problem is when you see the image below showing lines for rows that shouldn't/don't exist.
How do I get rid of the lines showing past row 6?
The generally accepted way of doing this is to add a footer view with a frame size of CGRectZero, as such:
[tableView setTableFooterView:[[UIView alloc] initWithFrame:CGRectZero]]
What this does is tell the table that there is a footer, and so it stops displaying separator lines. However, since the footer has a CGRectZero as its frame, nothing gets displayed, and so the visual effect is that the separators simply stop.
Swift Version
The easiest method is to set the tableFooterView property:
override func viewDidLoad() {
super.viewDidLoad()
// This will remove extra separators from tableview
self.tableView.tableFooterView = UIView(frame: CGRect.zero)
}
This is Because of Your Table-view Height. Weather you have Write
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
// Return the number of rows in the section.
return 6;
}
But its show rows According to Table-view Size. If you Dont want to show This extra Lines then Make UITableView Style Plain To Grouped.
Short and simple answer..
self.tableView.tableFooterView = [UIView new];
You could do something along the lines of:
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:7 inSection:0];
[self.mytableView cellForRowAtIndexPath:indexPath].hidden = YES;
Im sure there are some better ways but this is the first thing that came to mind.
If you're referring to the light gray lines that appear below the last row, that's simply the default way a UITableView draws the row separator.
You could try changing the Separator style in Interface Builder (see the images below) to see if one of those might be more to your liking.
You didn't say what you do want to see past the last row. If you just want to see the window background, then just embed your table view in a UIView that's just tall enough to show the number of rows you want to see. If you want to see more rows without scrolling, then you would have to adjust the size of that containing view based on the number of rows.
To programmatically remove it, use this:
[yourTableView setSeparatorStyle:UITableViewCellSeparatorStyleNone];
It's a lot easier to:
return numberOfSections + 1
return 0 rows in the final section
This keeps it simple!
This is related to another question of mine which wasn't answered in a helpful way (message when a UITableView is empty).
I'm trying to show an UIImage graphic that says You haven't saved any bookmarks over an UITableView when it's empty. I have NSNotification set-up so that when bookmarks are added or deleted, a message is sent so that the UITableView can be updated.
I've been trying to do it with this code. Why won't this work?
- (void)bookmarksChanged:(NSNotification*)notification
{
[self.tableView reloadData];
UIImageView* emptyBookmarks = [[UIImageView alloc] initWithFrame:CGRectMake(75, 100, 160, 57)];
emptyBookmarks.alpha = 1;
emptyBookmarks.image = [UIImage imageNamed:#"emptyBookmark.png"];
[self.view addSubview:emptyBookmarks];
[emptyBookmarks release];
if ([self.dataModel bookmarksCount] == 0)
{
emptyBookmarks.alpha = 1;
}
else
{
emptyBookmarks.alpha = 0;
}
}
I'm probably approaching this the wrong way... But if salvageable, what am I doing wrong?
When I initially have an empty bookmarks tableview, there's no image displayed. After I add a bookmark and then delete it, the image shows. Grrh.
Another way (and IMO the correct way) to do this is to manipulate the backgroundView property on the UITableView.
While making a single cell with a custom image cell would certainly works, I think it overly complicates the logic of your UITableViewController's data source. It feels like a kludge.
According to UITableView documentation:
A table view’s background view is automatically resized to match the
size of the table view. This view is placed as a subview of the table
view behind all cells , header views, and footer views.
Assigning an opaque view to this property obscures the background color
set on the table view itself.
While you probably don't want to just set it to your UIImageView, it is very easy to make a UIView that contains the UIImageView that you want.
Well first off if you were going to do it that way, you would need to reload the tableView after updating the image or model etc. and not before.
But you are probably making things more complicated than they need to be!
Why not just check to see if the data for section 0 and indexPath.row 0 are empty and if so in cellForRowAtIndexPath display a text message accordingly.
// First make sure there is always one row returned even if the dataModel is empty.
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSInteger numRows = 0;
if ([self.dataModel lastObject]) {
// Return the number of rows in the section.
numRows = [self.dataModel count]; // etc.
}
if (numRows < 1) numRows = 1;
return numRows;
}
// Then display the data if there is some, otherwise a message if empty.
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
if ([self.dataModel lastObject]) {
// setup the cell the normal way here.
} else { // the datasource is empty - print a message
cell.textLabel.text = nil;
cell.detailTextLabel.text = NSLocalizedString(#"You haven't saved any bookmarks", #"");
cell.detailTextLabel.textColor = [UIColor colorWithRed:0/255.0 green:0/255.0 blue:0/255.0 alpha:0.7];
cell.accessoryType = UITableViewCellAccessoryNone;
}
return cell;
}
Are you sure [self.dataModel bookmarksCount] is equal to 0 ?
While I agree that you are probably going about this the wrong way,
your image is allocated and added in your bookmark changed, your notification does not trigger when there are no bookmarks initially. Hence you don't see the image. Call the bookmar changed when your table view inits or appears.
Probably the best way to achieve this is to perform a check in your numberOfRowsInSection method to return 1 if your data source is empty. Then in cellForRowAtIndexPath check if your data source is empty and if it is, create a custom cell that contains whatever you want. In heightForRowAtIndexPath you need to return your custom cell height if your datasource is empty, but only if you want the cell larger than the default. At least that is how I would approach it.
when bookmarks count is nil add one to your row method:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
int c;
c = bookmarks.count;
if(c == 0){
c = 1;
}
return c;
}
and then the same check again in your cellforrowatindexpath.
Another thing to be aware of in this situation is that if you're using core data and you're datasource is feeding off an entity, you will want to make sure your model matches. You can get some weird side-effect behavior in certain situations. This is especially true if you allow editing and core data has an empty model but you're tableview is still showing a cell.
I have a tableView that needs to be updated after information has been inserted from another view. If I perform a
[self.tableView reloadData];
The very next time I insert more information in another view and try to reload the table, all the currently visible rows are duplicated.
In other words, when I start up the app I have:
tableView:
Row 1
Row 2
Then I submit some information that will also show up in the table and suddenly I have:
tableView
Row 1
Row 2
Row 3 <- info I just added
Row 1
Row 2
My numberOfRowsInSection implementation looks like this:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [ItemsController sharedItemsController].count;
}
My cellForRowAtIndexPath implementation looks like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
ItemsController* controller = [ItemsController sharedItemsController];
NSMutableArray* recentItems = controller.listOfRecentItems;
CustomCell *cell = nil;
NSUInteger row = [indexPath row];
if( row < recentItems.count )
{
Items* item = [recentItems objectAtIndex:row];
if( recentCellData == nil )
recentCellData = [[NSMutableDictionary alloc] initWithCapacity:[indexPath length]];
if( [recentCellData count] > 0 )
cell = [recentCellData objectForKey:[NSString stringWithFormat:#"%d", row]];
if (cell == nil) {
UIViewController * view1 = [[UIViewController alloc] initWithNibName:#"CustomCell" bundle:nil];
cell = (CustomCell*)[view1 view];
[recentCellData setObject:cell forKey:[NSString stringWithFormat:#"%d",row]];
}
// do some other stuff here
}
// Set up the cell
return cell;
}
What's the best way to update the table and avoid duplicating the currently visible rows.
Thank in advance for all the help!
The error isn't in how you're reloading the table, it's in how you're providing data to it. Set a breakpoint in the data source methods and the method that adds new rows to see where you're going wrong.
You'll only end up with five items if tableView:numberOfRowsinSection: returns 5. Thats the simple answer to your question, but I see other problems here. I'm wondering why you have this test: row < recentItems.count. Is that array the same thing as [ItemsController sharedItemsController].count? You really need to be using the same array for both methods.
(Also, it's not a syntax error, but you shouldn't use the property syntax for things that aren't declared as properties. You should write [recentItems count] instead.)
I'm also confused by the code you use to set up the cell. Cells are meant to be reusable. That is, you create one cell, then reconfigure it every time in your implementation of tableView:cellForRowAtIndexPath:. Your code creates a cell for each item in your list. This is very memory-inefficient, and will likely crash your program due to insufficient memory on the iPhone if you keep lots of cells in memory like this.
The recommended approach is to call dequeueReusableCellWithIdentifier:. If that returns nil, then you set up a cell using the initWithFrame:reuseIdentifier: initializer. The table view is very smart, and will only ask you to redraw the cell when it needs you to.
Your recentCellData dictionary looks really shaky to me, too. What if you insert an item after the item with key #"2"? All the items with key #"3" onward will need to be shifted one element to the right to work the way you expect. That's a ton of bookkeeping that seems rather unnecessary to me. If you really needed something like this -- and to be clear, I don't think you do -- why wouldn't you use an NSMutableArray, which is much easier to use?
I added a bit more info above.