I am using a simple UITableView and using separator as a image. When table is loaded initially it looks fine but when user scrolls up and leaves, the separator image disappears. Again when user scrolls down and leaves, lines appears again.
Please let me know how to resolve this.
- (UITableViewCell *)tableView:(UITableView *)aTableView cellForRowAtIndexPath: (NSIndexPath *)indexPath
{
static NSString *CellID=#"Cell"
MyTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:SwitchCellIdentifier];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
UIImageview *aSwitch = [[UIImageview alloc] initWithImage:[UIImage imageNamed:#"divider.png"]];
separator.frame = CGRectMake(0,50,320,1);
[cell.contentView addSubview:seperator];
}
..........
It's not clear where you declare "separator" but you'll want to make sure you initialize and allocate it as a separate instance for each cell.
UIView *separator = [[UIView alloc] initWithFrame:CGRectMake(0, 50, 320, 1)];
[cell.contentView addSubView:separator];
Are you trying to use one separator instance for all separators in the table? That won't work because a view can only be added to a single superview. You should initialize a new separator for each cell in your reuse pool.
Related
I didn't have this problem with iOS6, but am currently having it with iOS7. I have a UITableView and you can see 8 cells at the time the view is loaded. Each populated with different names from and array. If you scroll down, the next two cells look good, but everything past that gets text laid on top of it; That text being the contents of what was in the previous cells. So the 10th cell will have what was in the first cell, as well as what is supposed to be in the 10th cell laid on top of it.
Code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
//Create Label for Name inside cell
UILabel *name = [[UILabel alloc] initWithFrame:CGRectMake( 7.0, 5.0, 300.0, 30.0 )];
[name setText:[self.entriesArray objectAtIndex:indexPath.row]];
//Check to see if current person is a Parent or Child
NSString *class = [self.database getCellDataWithMembership:[self.MembershipArray objectAtIndex:indexPath.row] andColIndex:4];
if([class isEqualToString:#"CHILD"])
{
name.textColor = [UIColor colorWithRed:25.0f/255.0f green:111.0f/255.0f blue:45.0f/255.0f alpha:1.0f];
name.font = [UIFont fontWithName:#"Helvetica-Bold" size:17.0];
}
[cell.contentView addSubview:name];
return cell;
}
My skill with Table views is makeshift at best. I've been reading lots of documentation and researching solutions, but was not able to come up with a solution. I just find it odd that it works perfect for iOS6, but not for iOS7.
So it fetches a person's name from an array and I want to populate the cells with those names. I was able to originally accomplish this using:
cell.textLabel.text = [self.entriesArray objectAtIndex:indexPath.row];
if([class isEqualToString:#"CHILD"])
{
cell.textLabel.textColor = [UIColor colorWithRed:25.0f/255.0f green:111.0f/255.0f blue:45.0f/255.0f alpha:1.0f];
cell.textLabel.font = [UIFont fontWithName:#"Helvetica-Bold" size:17.0];
If I use that instead of the "name" UILabel actions from the first code block, then it displays the names perfectly with no text overlay, but what becomes an issue is the text color. If they are labeled as a CHILD then they should be green text and bold. However, after scrolling down, every person becomes green when they shouldn't be.
Sorry for the lengthy question. I've been working on this and racking my brain around it and I just can't seem to figure it out. Any help would be greatly appreciated.
I'm dynamically adding UI objects to cells. As "caglar" notes, adding and then removing is probs not the best-practice. But, I am doing this also. The way I get around adding loads of UI objects to the cell, each time it's displayed, is by removing all my subviews first. The willDisplayCell delegate then adds them back. Clearly, if you want to remove only certain views, you'll have to tag the view and be more selective with your removal. But you can remove all with the following.
-(void)tableView:(UITableView *)tableView
willDisplayCell:(UITableViewCell *)cell
forRowAtIndexPath:(NSIndexPath *)indexPath {
[[cell.contentView subviews] makeObjectsPerformSelector:#selector(removeFromSuperview)];
}
Just ensure you're adding / removing your labels to the cell's contentView. In iOS7, you'll remove that too, if you're not careful.
Hope it helps you out.
In your code, labels are added to cell whenever cellForRowAtIndexPath: method is called. I mean you add labels many times. You can remove the label which was added before.
//If label was added with tag = 500, remove it
for (UIView *sv in cell.contentView.subviews)
{
if (sv.tag == 500)
{
[sv removeFromSuperview];
}
}
//Create Label for Name inside cell
UILabel *name = [[UILabel alloc] initWithFrame:CGRectMake( 7.0, 5.0, 300.0, 30.0 )];
[name setText:[self.entriesArray objectAtIndex:indexPath.row]];
name.tag = 500;
However, this solution is not a good solution. I think creating a custom UITableViewCell is the right thing to do.
You can try this method, when the cell is nil, you need to creare the UILabel* name, then you set the name label with a tag name.tag = 1000, then you can access this label with this method UILabel* name = (UILabel*)[cell.contentView viewWithTag:1000];.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
//Create Label for Name inside cell
UILabel *name = [[UILabel alloc] initWithFrame:CGRectMake( 7.0, 5.0, 300.0, 30.0 )];
name.tag = 1000;
[cell.contentView addSubview:name];
}
UILabel* name = (UILabel*)[cell.contentView viewWithTag:1000];
[name setText:[self.entriesArray objectAtIndex:indexPath.row]];
//Check to see if current person is a Parent or Child
NSString *class = [self.database getCellDataWithMembership:[self.MembershipArray objectAtIndex:indexPath.row] andColIndex:4];
if([class isEqualToString:#"CHILD"])
{
name.textColor = [UIColor colorWithRed:25.0f/255.0f green:111.0f/255.0f blue:45.0f/255.0f alpha:1.0f];
name.font = [UIFont fontWithName:#"Helvetica-Bold" size:17.0];
}
return cell;
}
You can set uilabels by using ios6/7 delta shown is size inspector .firstly set your total view for ios7 by changing values x,y,width,height and then change value in ios6/7 delta to make it for ios6 .Hope you get
you may change the this code.
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath]; -> UITableViewCell *cell = nil;
I am loading custom separator image in uitableview cell.
Here is my code :
- (UITableViewCell *)tableView:(UITableView *)aTableView cellForRowAtIndexPath: (NSIndexPath *)indexPath
{
static NSString *CellID=#"Cell"
MyTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:SwitchCellIdentifier];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
UIImageview *aSwitch = [[UIImageview alloc] initWithImage:[UIImage imageNamed:#"divider.png"]];
separator.frame = CGRectMake(0,50,320,1);
[cell.contentView addSubview:seperator];
}
if(cell.height == 22)
{
/// here i am setting frame for uiimageview
}
but i am getting seperator image disappears for only one row out of 20 while scrolling.
Can you please help why it is loading like this.
If you've put your separator UIImage out of the bounds of the cell, and set cell.clipsToBounds = NO; to have the separator image displayed, the separator image might get hidden by drawing the next cell.
You can't control the z-index of the cells as they're being drawn on screen, it depends from where you're scrolling (bottom to top, or top to bottom).
If that's indeed you're issue, you can either put the divider inside the cell's frame, or if your separator is thin enough use:
[TableView setSeparatorColor:[UIColor colorWithPatternImage:[UIImage imageNamed:...]]];
self.tblView=[[UITableView alloc] initWithFrame:CGRectMake(0,0,320,370) //set as u need
style:UITableViewStylePlain];
self.tblView.delegate=self;
self.tblView.dataSource=self;
[self.view addSubview:self.tblView];
UIView *v = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 10)];//set as u ne
v.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"divider.png"]];
[self.tblView setTableHeaderView:v];
[self.tblView setTableFooterView:v];
[v release];
What makes scrolling so choppy on the UITableView? In my mind following code is a culprit. I am having very hard time to replace this logic with something other.
for (UIView *view in cell.contentView.subviews) {
[view removeFromSuperview]; }
This is what I am doing.
- (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];
}
for (UIView *view in cell.contentView.subviews) {
[view removeFromSuperview];
}
BGMArticleAbstract *articleAbstract = [self.section.articleAbstracts objectAtIndex:indexPath.row];
[cell.contentView addSubview:[self getHedlineFromArticleAbstract:articleAbstract]];
[cell.contentView addSubview:[self getThumbnailImageFromArticleAbstract:articleAbstract]];
[cell.contentView addSubview:[self getAbstractParaFromArticleAbstract:articleAbstract]];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
return cell; }
I am doing, addSubview to contentview because I am creating a dynamic cell height. Is there any way I can make this scroll view work smooth ? Thank you for your help.
You should design your cell as you need it. Add labels and whatever you need to the cell, and then change the content of these already available subviews.
If you need to display an image, add once an UIImageView to the cell and only change the image property of it. Same for text fields and so on.
The way you do it makes the built-in cache useless, because you regenerate all subviews again and again..
To boost the performance even more, you can do the drawing of the cell by yourself.
Apple has a quite nice example project:
http://developer.apple.com/library/ios/#samplecode/AdvancedTableViewCells/Introduction/Intro.html
You are right that the problem is caused by how you return cells. The correct pattern is as follows...
- (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];
}
// see if cell contains our image views. A reused cell will, but a new cell won't
UIImageView *imageViewA = (UIImageView *)[cell viewWithTag:32];
UIImageView *imageViewB = (UIImageView *)[cell viewWithTag:33];
UIImageView *imageViewC = (UIImageView *)[cell viewWithTag:34];
if (!imageViewA) {
// the cell must be new, so create it's image views
// you should be able to borrow most of this code from your getHeadline/thumbnail/etc methods.
// the good news is that this relatively expensive code runs only for new
// cells and there are only a few of those - only enough to fill the visible frame
imageViewA = [[UIImageView alloc] initWithFrame:CGRectMake(/* frame it here */)];
[cell.contentView addSubview:imageViewA];
imageViewA.tag = 32;
imageViewB = [[UIImageView alloc] initWithFrame:CGRectMake(/* frame it here */)];
[cell.contentView addSubview:imageViewB];
imageViewB.tag = 33;
imageViewC = [[UIImageView alloc] initWithFrame:CGRectMake(/* frame it here */)];
[cell.contentView addSubview:imageViewC;
imageViewC.tag = 34;
// this too, need only be done upon creation
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
// now, whether it's a new cell or a reused cell, we have image views
BGMArticleAbstract *articleAbstract = [self.section.articleAbstracts objectAtIndex:indexPath.row];
// change your methods getHeadline... getThumbnail... etc to answer UIImages
// not UIImageViews, which are setup only for new cells
imageViewA.image = [self getHedlineFromArticleAbstract:articleAbstract]];
imageViewB.image = [self getThumbnailImageFromArticleAbstract:articleAbstract]];
imageViewC.image = [self getAbstractParaFromArticleAbstract:articleAbstract]];
// as a side note, once you get these methods returning images (more like model objects)
// rather than image views (view objects) they might be more appropriately placed
// in the BGMArticleAbstract class rather than the view controller
return cell;
}
In a normal situation when working with a UITableView I have the standard code for reusing old cells:
- (UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"Cell";
UITableViewCell *cell = [tv dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
return cell;
}
I noticed, however, that in the case when I added subviews to the cell that they weren't deleted and that a new view were added every time. I have an example below that demonstrate it perfectly:
- (UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"Cell";
UITableViewCell *cell = [tv dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil)
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
UILabel *label = [[UILabel alloc] init];
label.text = #"HELLO";
label.frame = CGRectMake(arc4random() % 50, -1, 286, 45);
label.backgroundColor = [UIColor clearColor];
// Add views
[cell addSubview:label];
return cell;
}
I need some code that reuses my labels again in the same way the cells are being reused. What should I do?
Thanks
You must only add the subviews if you are making a new cell. If you are dequeuing, the subview is already present and should not be re-created.
Your method should be:
- (UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"Cell";
UITableViewCell *cell = [tv dequeueReusableCellWithIdentifier:cellIdentifier];
UILabel *label;
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
label = [[UILabel alloc] init];
label.tag = 1;
// Add views
[cell addSubview:label];
}
else
{
// Label will already exist, get a pointer to it
label = [cell viewWithTag:1];
}
// Now set properties on the subview that are unique to each cell
label.text = #"HELLO";
label.frame = CGRectMake(arc4random() % 50, -1, 286, 45);
label.backgroundColor = [UIColor clearColor];
return cell;
}
Note how the label is only created when the cell is nil. Otherwise, it is found using the tag.
I need some code that reuses my labels again in the same way the cells
are being reused.
No, you need to understand the table view design better. It should be obvious why the views are being added multiple times – reusing a cell means that you take a previous instance of UITableViewCell that’s no longer needed (thus saving a costly allocation of a new object) and reuse this instance for the new cell. But this previous instance already has the label attached to it, so the number of labels grows.
I would subclass UITableViewCell and put the label creation inside the initialization code for this new class. (Or create a UIView subclass and set it as the cell’s contentView, as suggested in this nice table tutorial by Matt Gallagher.) That’s the proper way to encapsulate the view details and hide them from the table data source.
you can use something like in the else part for if(cell == nil)
for (UIView *sub in [cell.contentView subviews])
{
if([UILabel class] == [sub class])
NSLog(#"%#",[sub class]);
UILabel *label = (UILabel *)sub;
//do label coding ie set text etc.
}
I use lazy initialization of views within my custom table cell class.
It only needs to load views and "addSubview" once.
- (void) lazyInitTitleLabel {
if (_titleLabel != nil) {
return;
}
_titleLabel = [[UILabel alloc] initWithFrame: CGRectMake(10.0f, 10.0f, 200.0f, 30.0f)];
// Cell adds the label as a subview...
[self addSubview: _titleLabel];
}
The only thing you need to be careful about is resetting any content that views display like text in your labels and images in your image views. If you don't old content may get reused along with the recycled table cells.
Good luck!
Might be a stupid question.
I have a UITableview, with multiple cells. In each cell I am displaying some data. I am not using cell's text property to display data. Instead I have a custom label inside my cell, which is displaying the text.
My question is:
When I click on the cell, I need to retrieve the data from the cell. How can I do this.
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
UILabel *CellTextlabel = [[UILabel alloc] init];
CellTextlabel.tag = 222;
[CellTextlabel setFrame:CGRectMake(40, 5, 200, 20)];
[cell.contentView addSubview:CellTextlabel];
[CellTextlabel release];
}
UILabel *editCellTextlabel = (UILabel *)[cell.contentView viewWithTag:222];
editCellTextlabel.font = [UIFont boldSystemFontOfSize:18];
editCellTextlabel.text = contact.lastName;
In your didSelectRowAtIndexPath method, you may do it as follows:
UITableViewCell *cell = (UITableViewCell *)[self.tableViecellForRowAtIndexPath:indexPath];
UILabel *textLabel = (UILabel *)[cell viewWithTag:222];
Now you can retrieve the data in the cell's UILabel using textLabel.text
You could get access to that label in didSelectRowAtIndexPath: with
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
UILabel *myLabel = [cell.contentView viewWithTag:222];
But probably worth asking, why are you adding a sub label instead of using the textLabel property? you can modify its frame, settings etc and then you don't have to worry about tags, since this property is exposed in UITableViewCell by default
In the -tableView:didSelectRowAtIndexPath: method, you can get the data from your tableView's array:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
id objectForCell = [self.myArray objectAtIndex:indexPath.row];
//do what you want with the above data.
}