I used a tutorial online to create a slide out side bar (similar to the facebook app).
It's based on using a table view as the side bar.
I cannot change the size (row height) of an individual cell as the table is set to dynamic (as specified by the tutorial. I change the row height in the IB and it makes no difference when running. It turns out I need a static table to use this.
When I change the table to static, it breaks my app with the following code causing the problem. I know a dynamic table is when you want to reuse cells and therefore dequeueReusableCell will cause a problem.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *CellIdentifier = [self.menuItems objectAtIndex:indexPath.row];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
return cell;
}
I don't have much experience with TableViews past this specific tutorial so just need a little bit of help amending the code so I can use a static table.
Thanks
If your table view isn't static, don't make it static to handle the row height. Instead, implement the table view delegate method tableView:heightForRowAtIndexPath: and return the appropriate height for each row.
Setting the height in the XIB / storyboard can have an effect but it depends on the overall configuration as to exactly what (if anything) it will do.
Related
Hello guys i think almost everyone who is in ios development may come across the issue of reuse of the UITableCell by using following code line.
RZRestaurantListingCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
I have search lot about this but not getting any desire answer so please help me out in this case.
I have the same issue as most of iPhone developer having after reusing the cell.
I have the UIProgressView inside my cell and one button is there for downloading the video and i am showing the progress there in progress view how much is left.
So Now what i have problem is when i have more data and going out of the screen at that time i am press the download button on very first row of the UITableviewCell then i am scrolling down so the progress also shown in bottom random one cell so the UI changes in two cell rather then one.
You need to implement -prepareForReuse method in your custom cell class and set all cell properties to default value.
- (void)prepareForReuse
If a UITableViewCell object is reusable—that is, it has a reuse
identifier—this method is invoked just before the object is returned
from the UITableView method dequeueReusableCellWithIdentifier:. For
performance reasons, you should only reset attributes of the cell that
are not related to content, for example, alpha, editing, and selection
state. The table view's delegate in tableView:cellForRowAtIndexPath:
should always reset all content when reusing a cell. If the cell
object does not have an associated reuse identifier, this method is
not called. If you override this method, you must be sure to invoke
the superclass implementation.
Refer here for more, https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableViewCell_Class/#//apple_ref/occ/instm/UITableViewCell/prepareForReuse
You need to assign a progress value inside the - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
RZRestaurantListingCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// If the cell is reused, the `-prepareForReuse:` of `UITableViewCell` will be called.
//!! Assign current progress value to this cell, otherwise, the progressBar.value may look like a random value.
//!! Because the current cell is reused from a disappeared cell.
cell.progressBar.value = ... ;
return cell;
}
The design may be complex, because the progress may be updated continuously when the cell is on the screen.
Use prepareforreuse method to clear content of cell before using it... e.g.
-(void)prepareForReuse
{
[super prepareForReuse];
self.textLabel.text = #"";
self.detailTextLabel.text = #"";
self.imageView.image = nil;
}
Current I am creating a prototype cell in storyboard and using this cell as a section header.
Inside tableView:viewForHeaderInSection: method, I am dequeuing the cell and returning it.
My section header cell has a UITextField and a UIButton in it.
When I tap on text field keyboard appears but as soon as focus is moved away from text field whole section header disappears.
This happens when I return the cell directly as section header view, but if I return a newly allocated UIView as section header view onto which cell is added as subview then everything works fine besides autoresizing masks.
Why header is disappearing?
I am not sure what could be the best thing todo here.
-(UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
static NSString *CellIdentifier = #"SectionHeader";
SettingsTableViewCell *sectionHeaderCell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
//return sectionHeaderCell; // returning cell directly, section header disappears when focus is moved away from text field.
UIView * headerView = [[UIView alloc] initWithFrame:sectionHeaderCell.frame];
[headerView addSubView:sectionHeaderCell];
return sectionHeaderCell;//header view never disappears, but auto resizing masks do not work. Need to know how to set autoresizing masks to headerView so that it resizes correctly.
}
Prototype cell table views only allow you to design cells in the storyboard editor, not section headers and footers. Your attempt to use a UITableViewCell as the section header is a clever hack, but it's just not supported by the classes involved—UITableViewCell is not designed to be used for anything other than a table view cell. It could do a lot worse than the view disappearing or not being laid out correctly; UIKit would be well within its rights to fail an assertion, delete all the app's data, revoke your developer certificate, or set your house on fire.
If you want your code to function properly, your choices are to either create your section headers in code or to put them in a separate XIB file. I know that's not what you want to do, but those are the options you have.
I had the same issue and the fix was to return the cell's contentView like:
-(UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
static NSString *CellIdentifier = #"SectionHeader";
SettingsTableViewCell *sectionHeaderCell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
sectionHeaderCell.myPrettyLabel.text = #"Greetings";
sectionHeaderCell.contentView.backgroundColor = [UIColor whiteColor]; // don't leave this transparent
return sectionHeaderCell.contentView;
}
And you get the same autolayouted results as before, but without the disappearing.
I am sure you can use UITableViewCell as a section header, because UITableViewCell is subclass of UIView, so according to LSP
“objects in a program should be replaceable with instances of their
subtypes without altering the correctness of that program.”
In iOS 8, it's simple really. Just design your header the same way you design your cell. Everything is the same, you can put custom class and don't forget to add reuse identifier.
When it comes to use it in the code, just return that cell in tableView:viewForHeaderInSection method.
Don't forget to implement tableView:heightForHeaderInSection if you want to use fix height or tableView:estimatedHeightForHeaderInSection if the height depends on the cell intrinsic size.
In this project I have absolutely no code. In my main.storyboard I have a TableViewController with so far 1 cell. In that one cell I put an Image View in, then I selected the certain picture. The cell is 320 (Width) by 44 (Height). Everything seems fine in the main.storyboard, however I press run, the app opens but there is nothing there, only a bunch of lines.
Any help would be great I will give screenshots to anyone who needs them in order to help me solve this problem. I am using xCode 5.1
If you don't want to write any code than you must tableView type to static!
Check that.
Here's the snippet for TableViewDelegate. Hope this will help. Don't forget to thumbs up
Make sure you have this in your TableView
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
return 1; ---->> should return 1
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return 10; ----->> return how many rows you want to show, mostly you write
return yourarray.count;
}
I think the problem will be in the method below
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UITableViewCell *cell = nil; ---->> Instead of UITableViewCell you need to
change to the class name of the
TableCell ( This is where your cell is
created)
cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
if(!cell){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
reuseIdentifier:#"Cell"]; ---->>Instead of UITableViewCell you need to
change to the class name of the
TableCell ( This is where your cell is created)
}
cell.textLabel.text = #"Cell";
return cell;
}
You have to use either a static tableview that uses predefined cells or (by default) use a dynamic tableview - in that case you have to provide the cells in code by adhering to the tableviews data source protocol. Which you seem to not be doing now.
So, in interface builder, set the tableview to be static and you can build the cells in interface builder and they will be displayed. Make sure you delete the boilerplatecode in table viewcontroller that is given to you to easily implement the protocol (if you don't delete it, the default code returns nil off the cells and so none will get displayed).
When you get it working, find a nice tableview tutorial. I suggest ray wenderlich or the cs193p course on itunesU.
I am setting up my UITableView using storyboard editor. For creating my cells I am using the standard delegate method:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"SearchResultCell"];
if (cell == nil)
{
// Do cell setup
}
// etc
return cell;
}
Except when the cell is dequeued the very first time it's not nil, as it should be. So the code inside the if statement is never executed.
People get this error when their reuse identifiers are inconsistent, so I went ahead and verified that I am using the exact same reuse identifier in my storyboard views as I do in my code. Still facing the issue. I also have several tableviews within the project and each one has a unique reuse identifier. Still no dice. Anyone know anything else that could be wrong here?
That's not how UITableView works anymore. Reading your question, I think you might be confused about how it worked before as well. If not, sorry, the first part of this is just review. :)
Without storyboard cell prototypes
Here's how it used to work:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
// If the tableview has an offscreen, unused cell of the right identifier
// it will return it.
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"SearchResultCell"];
if (cell == nil)
{
// Initial creation, nothing row specific.
}
// Per row setup here.
return cell;
}
Here when you create the cell using the reuse identifier, you do only the initial setup here. Nothing specific to this particular row/indexPath.
Where I've put the Per row setup comment you have a cell of the right identifier. It may be a fresh cell, or a recycled cell. You're responsible for all setup related to this particular row/indexPath.
Example: if you set the text in some rows (likely) you need to set or clear it in all rows, or text from rows you set will leak through to cells you don't.
With storyboard prototypes
With storyboards, though, the storyboard and table view handle the initial cell creation! This is brilliant stuff. You map out your cell prototypes directly in the tableview when using storyboards, and Cocoa Touch will do the initial creation for you.
Instead, you get this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"SearchResultCell"];
// You'll always have a cell now!
// Per row setup here.
return cell;
}
You're responsible for all the same per row setup as before, but you shouldn't need to write code to build your initial empty cell, either inline or in its own subclass.
As Ian notes below, you can still use the old approach. Just make sure not to include a cell prototype in the storyboard for the identifier you specify. The view controller won't be able to build your cell from the cell prototype, dequeueReusableCellWithIdentifier will return nil, and you'll be exactly where you were before.
I have a uitableview with each cell having a scroll view as the subview.
the scrollview has a bunch of images in it.
so when i change the data in the data source and after calling the reload table
the images doesn't change but when i remove the dequeue the new data is reloaded.
is there any method to remove the contents in the dequeue so that i don't get the old data
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"looser"];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
scrollview=[[myscrollView alloc]initwitharray:imagearray];
[cell.contentView addSubview:scrollview];
}
}
A tableview works as follows:
It has room for a certain amount of cells on the screen, let's say 7 as an example. The tableview will ask you for the 7 cells of indexes 0 through 6.
If the top cell leaves the screen by scrolling, it will be placed in the reusable cell queue. There are now 6 cells on the tableview.
A new one comes up at the bottom now, the tableview asks for the cell at index 7. You call dequeueReusableCell, and you get the one that was at the top earlier.
The tableView has no idea what your cell is like, as it can be subclassed, so it will not make any changes to it. It is up to you to use your knowledge of how the tablecell is constructed to empty it, then fill it with the correct new data.
The reason tableview works like this is for performance. In stead of having maybe 100 views that would have to be checked (or mostly, ignored, which also costs time) for every scroll movement, it has a maximum of 7.
So in short, no. There are no default methods to remove data from reusable cells in UITableView, since UITableView can not and should not know what kind of cells they are. It is up to you to clear the cells when the tableview gives them to you.
Create a custom cell and it generates a method
- (void) prepareForReuse{}
Which do you cleanse all data from a cell and the output will be an empty cell.
No, not while the cell is in the cache. When you dequeue a reusable cell you should clear out the old data first before using it again.
Maybe you should just remove the stuff you don't want.