I have this problem when deploying my application on iphone, which wasn't detected on the simulator.
this the code of the cellforrow...
- (UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"beginning cellforRowAtIndexPath for section %d, and cell %d",[indexPath indexAtPosition:0],[indexPath indexAtPosition:1]);
static NSString *MyIdentifier = #"MyIdentifier";
NSString *fieldTitle;
NSString*fieldDescription;
[_stopWatch start];
[PersonalSection GetField:&fieldTitle AndValue:&fieldDescription UsingIndexPath:indexPath AndPersonalInformation:_personalInfo];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil) {
[[NSBundle mainBundle] loadNibNamed:#"ViewContent" owner:self options:nil];
cell = tvCell;
self.tvCell=nil;
((UILabel*) [cell.contentView viewWithTag:1]).layer.cornerRadius=11;
((UILabel*) [cell.contentView viewWithTag:2]).layer.cornerRadius=11;
}
UILabel*mainLabel=(UILabel*) [cell.contentView viewWithTag:1];
mainLabel.text=fieldTitle;
//mainLabel.textColor = [UIColor colorWithRed:0.745 green:0.116 blue:0.176 alpha:1.0];
UILabel*detailLabel=(UILabel*)[cell.contentView viewWithTag:2];
detailLabel.text=fieldDescription;
[_stopWatch stop];
NSLog(#"---------End cellforRowAtIndexPath");
return cell;
}
the rest is for sections and it's like return 3 or 5 no real bottleneck there.
so i'm wondering what's slowing it so much.
now the data fetching "[PersonalSection GetField:&fieldTitle..." is rather fast, it takes on the iphone maximum 0.1 ms. The problem is somewhere else, i'm guessing there's a way for optimizing this code, and i'm wondering about the custom cell influence it's only a cell with label and textfield linked to this ViewController.
Any ideas.
When you create the cell you're setting the identifier to #"cell" but when you dequeue it you're looking for #"MyIdentifier". It looks like you're recreating the cell every time though this.
Ok, the main performance issue was rounding the corners of the subviews of the contentview.
using QuartzCore:
#import <QuartzCore/QuartzCore.h>
((UILabel*) [cell.contentView viewWithTag:1]).layer.cornerRadius=11;
I removed those and decreased the sizes of the controls to fit inside the cell of a sectioned table. and now they look round but the textfield and label are not.
this has fixed my scrolling performance noticeably.
Thank you all for your help.
Related
To sum it up, I'm facing 2 problems, the 1st is that time to time some cells disappear from the tableview and reappear randomly. The 2nd is a scrolling performance issue on iPhone 4 and below.
1st problem :
I am displaying a simple list of elements in an UITableView by adding a subview the [cell contentView]. Most of the time it works well, but sometimes when i scroll (and really randomly) a cell disappears.
Because this cell which "disappeared" is reused, the reused cell will also be "blank" when I scroll. And randomly again a cell can reappear/disappear while scrolling.
Here is my code for the cellForRowAtIndexPath: method :
- (UITableViewCell *)tableView:(UITableView *)_tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [_tableView dequeueReusableCellWithIdentifier:CellIdentifier];
LBSelectorChampionViewController *item = [self itemAtIndexPath:indexPath];
if (cell == nil) {
NSLog(#"CELL NIL");
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
[[item view] setTag:99];
[[item champName] setTag:50];
[[item champImage] setTag:51];
[[item buttonFavorite] setTag:52];
[[cell contentView] addSubview:[item view]];
}
UILabel *championLabel = (UILabel*)[[[cell contentView] viewWithTag:99] viewWithTag:50];
LBFavoriteChampionButton *buttonFavorite = (LBFavoriteChampionButton*)[[[cell contentView] viewWithTag:99] viewWithTag:52];
UIImageView *championImage = (UIImageView*)[[[cell contentView] viewWithTag:99] viewWithTag:51];
// Text
[championLabel setText:[item displayValue]];
[championImage setImageWithURL:[NSURL URLWithString:[item imageUrl]]];
// Fav button
[buttonFavorite setCurrentChampion:item];
if ([[self favoritesChampions] containsObject:item]) {
[buttonFavorite setSelected:YES];
[buttonFavorite setIsFavorite:YES];
} else {
[buttonFavorite setSelected:NO];
[buttonFavorite setIsFavorite:NO];
}
return cell;}
}
I've tried to log everything, I checked if "item" could be sometimes null and it's never the case. But when a cell disappears, the [[[cell contentView] subviews] count] is equal to 0, which normally should be 1.
I really don't understand what's happening here. I tested it on real devices + simulator and it happens with both of them.
2nt problem :
My other "problem" is that the scrolling of the tableview is not as smooth as i would expect it to be on the iPhone 4 (tested on iOS 6 and iOS 7, same result :-( ). I'm using SDWebImage to load images asynchronously and to cache them, I'm reusing cells, what could I do to improve the performances ? I tested on an iPhone 4S and had no problem, scrolling is very smooth.
Am I doing something wrong ? Any ideas about one of my problem ?
Thank you for taking the time to answer me.
EDIT : 1st attempt to solve the problem
Trying to customize cell with a custom UITableViewCell subclass :
- (UITableViewCell *)tableView:(UITableView *)_tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"LBListChampionCell";
LBListChampionCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil){
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"LBListChampionCell" owner:self options:nil];
cell = [topLevelObjects objectAtIndex:0];
}
LBSelectorChampionViewController *item = [self itemAtIndexPath:indexPath];
[[cell championName] setText:[item displayValue]];
[[cell championLogo] setImageWithURL:[NSURL URLWithString:[item imageUrl]]];
return cell;
}
I wasn't able for the moment to reproduce the "disappear" bug (sometimes it takes a moment to reproduce it...), but there is no improvement at all concerning the performances :(. Even while just setting a dummy text : [[cell championName] setText:#"Test"]; (and commenting the item part) the scrolling is still not really smooth.
Any ideas ?
EDIT 2 : Best solution (thanks to rdelmar)
Create a subclass of UITableViewCell and load the nib in viewDidLoad :
- (void)viewDidLoad
{
...
UINib *nib = [UINib nibWithNibName:#"LBListChampionCell" bundle:nil];
[[self tableView] registerNib:nib forCellReuseIdentifier:#"LBListChampionCell"];
}
- (UITableViewCell *)tableView:(UITableView *)_tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
LBListChampionCell *cell = [tableView dequeueReusableCellWithIdentifier:#"LBListChampionCell"];
LBSelectorChampionViewController *item = [self itemAtIndexPath:indexPath];
[[cell championName] setText:[item displayValue]];
[[cell championLogo] setImageWithURL:[NSURL URLWithString:[item imageUrl]]];
...
}
It increased the scrolling performance (still not perfectly smooth on iPhone 4 but it works well). Moreover it seems that no cell are disappearing anymore :-)
Thanks rdelmar!
I think somehow LBSelectorChampionViewController *item = [self itemAtIndexPath:indexPath]; from one of your cell's contentView was added to another cell's contentView, which would cause the previous cell's contentView to have 0 subview.
I think you are getting the first problem because of cell reusability. LBSelectorChampionViewController *item = [self itemAtIndexPath:indexPath]; will not always be added to the [cell contentView] as cell may not be nil. In addition, there might be a situation when this view will be added to another cell and removed from the previous. Anyway, this will be easier to fix if you subclass UITableViewCell and make LBSelectorChampionViewController part of this custom cell. This will make everything easier and you will never meet reusability problems.
I am not exactly familiar with SDWebImage, but maybe the problem is that it doesn't cache images and tries to load new image every time [championImage setImageWithURL:[NSURL URLWithString:[item imageUrl]]]; is hit. I've used AFNetworking in a few projects to load images and have never had any problems with it.
Hope this is helpful!
Cheers!
I have a problem, setting a button to a UITableviewCell.
After viewDidLoad, the button is on the right place. But when I am scrolling down, the button is anyplace else.
Here is my code, I hope you can help me.
Thanks In Advance.
- (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 (indexPath.section == 0 && indexPath.row == 0 && _isAddImageViewLoad == NO) {
// Add Image Button
UIButton *addImage = [UIButton buttonWithType:UIButtonTypeCustom];
UIImage* image = [UIImage imageNamed:#"AddImage#2x"];
addImage.frame = CGRectMake(110.0f, 10.0f, 110.0f, 110.0f);
[addImage setImage:image forState:UIControlStateNormal];
[cell.contentView addSubview:addImage];
_isAddImageViewLoad = YES;
} else {
NSDictionary *dictionary = [_items objectAtIndex:indexPath.section];
NSArray *array = [dictionary objectForKey:#"data"];
NSString *cellValue = [array objectAtIndex:indexPath.row];
cell.textLabel.text = cellValue;
}
return cell;
}
It is because you are reusing the cells, and the button is getting placed when it shouldn't an easy solution in your else section. Write addImage.hidden = YES; and in your if statement put addImage.hidden = NO;
Just a couple things. If you use "AddImage" it will use the "AddImage#2x" automatically if it's a retina display. I don't think that will solve your issue but it could be causing weirdness.
When a table view cell is scrolled off the view it is "recycled" in a sense. It appears like you are using a bool to exclude the original cell from being loaded again with a button. You may want to use a header to hold your button if you always want it at the "top". You may also want to verify that the button is being removed when the cell is reused. if its not it will show up in the next row that reuses that cell.
On a side note... Buttons don't usually work very well in table view cells because they handle touches in very different ways. It's quite a bit of modification to get them to feel natural but that's another matter.
Hope that helps!
The problem is because of cell reuse. You need to put some code in the else clause to delete the button if it exits. One way to do this, would be to give your button a tag, like:
addImage.tag = 10;
Then in your else clause:
}else{
if (cell viewWithTag:10) [[cell viewWithTag: 10] removeFromSuperview];
...
The problem is because of the dequeue for the cells. The first time the tableview creates the cells, all the cells run through the
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
code. But when the section 0 row 0 is moved off the screen, that cell is pushed into the cell reusable queue.
Now when your tableview needs to display section 0 row 0, it will get a cell from the reuse queue. you will not get the same cell as the first time. So now you might have 2 cells with the button.
What you should do is have different CellIdentifier for section 0 row 0 , and all other sections and rows. Also create the button when creating the cell. So after the first time the tableView creates the cell, you will not be creating the the button everything.
Look at this line of code:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
This line of code means the UITableViewCells are not created every time. They are re-used as you scroll up and down. Using the code you have above, the UIButton will be created in the correct spot, but then as the cells are re-used, it will create the button in random spots.
One quick way to solve the problem, change the above line of code to simply
UITableViewCell *cell;
My tableView scrolls with lags if extra populated. Up to 20 cells go well, but above - it starts lagging while scrolling. Please, suggest an implementation with a better scrolling result. Here is the way I did it:
I have defined a custom UITableViewCell class.
The cell has 4 labels and an imageView (each outlet is a synthesized property):
I have placed a tableView in my viewController, and populated it like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"CustomCell";
MyCustomCell *cell = (MyCustomCell *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"MyCustomCell" owner:self options:nil];
for (id currentObject in topLevelObjects)
if ([currentObject isKindOfClass:[UITableViewCell class]]){
cell = (MyCustomCell *) currentObject;
break;
}
}
[cell.label_descr setText:#"bla-bla-bla"];
[cell.label_date setText:#"bla-bla-bla"];
[cell.label_time setText:#"bla-bla-bla"];
[cell.label_numeric setText:#"bla-bla-bla"];
[cell.image_view setImage:[UIImage imageWithContentsOfFile:#"bla-bla-bla"]];
return cell;
}
The amount of text in each cell, as you can see, is miserable, and the image used for the UIImageView is about 25x25 .png file.
My tableView is supposed to hold more than 300 cells (don't blame on me, I have a "customer from hell").
Please, suggest a way to make the tableView scroll smoother, without (much) lags. Or an alternative way to present those "damn-over-300-cells" to my "from hell" customer.
300 thanks in advance!
P.S.: sorry if duplicated, but the solutions found didn't help at all.
EDIT:
About the image used for the imageView:
I use 2 different images only:
a "checkmark" - transaction done
and a "pending" - transaction in process
Maybe I use to define 2 imageView outlets in my tableViewCell xib, and just selecting the needed imageView, instead of setting each time the required image?
SOLUTION FOUND, thanks to everybody, especially to iNoob and max_.
In tableViewCell's xib, I have set the "checkMark" as the default image of the imageView.
When defining the cell's values, in cellForRowAtIndexPath, only if needed, I say:
if_I_should_present_a_pending_image:
[cell setPending];
to replace the "checkMark" with a "pending" image (method defined in tableViewCell class):
- (void)setPending{
self.image_view.animationImages = [NSArray arrayWithObjects:
[UIImage imageNamed:#"pending_1.png"],
[UIImage imageNamed:#"pending_2.png"],
[UIImage imageNamed:#"pending_3.png"],
[UIImage imageNamed:#"pending_4.png"],
nil];
self.image_view.animationDuration = 2.0;
self.image_view.animationRepeatCount = 0;
[self.image_view startAnimating];
}
l
After that, the table scrolls like a charm. Thanks to everybody again. Cheers.
Don't iterate through all of the subviews: cell = [topLevelObjects objectAtIndex:0];
Load the images in the background using gcd, and store them in an NSDictionary for easy access:
Pseudo code:
If caches dict contains an object for the URL you want to load
Retrieve that image from the dict
Set it as the image
Else
Load the image using dispatch_async()
Add it to the dict
I found this article suggesting that creating the cells programatically instead of using a nib file could be up to 5-10% faster. I don't know if it's true or not, so take it with a grain of salt, but it may be worth a try.
Replace your code with following one and try it out.
For the below code :
1) Take IBOutlet of your UITableViewCell in the your controller. for below code it is myCustomTableViewCell.
MyCustomCell *customCell = (MyCustomCell *)[tableView dequeueReusableCellWithIdentifier:#"MyCustomCell"];
if(customCell == nil) {
[[NSBundle mainBundle] loadNibNamed:#"MyCustomCell" owner:self options:nil];
customCell = myCustomTableViewCell;
}
Hope it will work.
In the interface designer, I have a very simple setup. The main view (which is a table cell view) has four sub-views, all siblings: UIImageView and three UILabels. I'm using UIImageView to display the background of the table row. I set it so that UIImageView is at the very back of the z-index tree and set its alpha to 0.2 to dim the image - and UILabel's are going over it.
If I set the image into the imageview at the design time in interface designer, then everything is fine, however if I set the image into the imageview at design time (I receive the actual image from the server), then the imageview alpha setting is ignored, the image is displayed at alpha = 1 and the uiimageview is displayed over all the labels. I even tried to use [parent sendSubviewToBack:imageView] but it didn't help.
What am I missing? Here's my whole code for displaying the table row.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[NSBundle mainBundle] loadNibNamed:#"OOItemInfoCell" owner:self options:nil] lastObject];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
OOXMLNode *infoNode = [searchItemList objectAtIndex:indexPath.row];
[(UILabel *)[cell viewWithTag:2] setText:[itemNode elementNodeWithKey:#"title"].value];
[(UILabel *)[cell viewWithTag:3] setText:[itemNode elementNodeWithKey:#"intro"].value];
[(UILabel *)[cell viewWithTag:4] setText:[NSString stringWithFormat:kThemeAge,
[itemNode elementNodeWithKey:#"theme"].value,
[itemNode elementNodeWithKey:#"age"].value]];
UIImageView *bgview = (UIImageView *)[cell viewWithTag:0];
[bgview setImage:[itemNode imageFromKey:#"background"]];
[cell sendSubviewToBack:bgview];
return cell;
}
Ok, this was pretty stupid of me... I had the tag of the UIImageView set to 0 and then was using viewWithTag:0 to find that view. Yet, the parent view also had tag 0, so instead of my background UIImageView, the entire cell was being set to the image (I wouldn't think that a table cell view would respond to setImage - but it did.
I now changed the tag on UIImageView to 5 - and everything is hunky-dory.
I want to display multiple columns in a UITableView.
For Example:
TableView
FName LName Age
----- ----- ---
Abby Michale 34
I think the correct way of doing this is UICollectionView. Started with UITableView and finally failed at some point due to unexpected behavior while trying to implement scrolling both left-right and up-down.
Please check this awesome post for a complete and up-to-date solution:
http://www.brightec.co.uk/blog/uicollectionview-using-horizontal-and-vertical-scrolling-sticky-rows-and-columns
Result will be like this:
You can define a custom cell in IB, which will contain 3 labels and in function:
- (UITableViewCell *)tableView:(UITableView *)aTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *DetailCellIdentifier = #"DetailCell";
UITableViewCell *cell = [aTableView dequeueReusableCellWithIdentifier:DetailCellIdentifier];
if (cell == nil) {
NSArray *cellObjects = [[NSBundle mainBundle] loadNibNamed:#"DetailCell" owner:self options:nil];
cell = (UITableViewCell*) [cellObjects objectAtIndex:0];
}
// setup your cell
}
when you define the cell in IB give each label a tag, so when you need to put a text there you can retrieve it by tag like this:
label = (UILabel *)[cell viewWithTag:NAME_TAG];
label.text = myObject.name;
and repeat this with other 2 labels. The tag is a unique number.
Put this code instead //setup your cell comment
I have created UIGridView. I believe your problem can be solved using the same technique.
You can learn the source code of UIGridView. The code is really short.
Bit late to the party, but we've open sourced our fully featured table component:
https://github.com/flexicious/iOSDataGrid
Some screenshots:
http://www.ioscomponents.com/Home/IOSDataGrid
Feel free to use!
Create a custom UIView subclass containing, say, three UILabel elements as subviews. Then set the cell's contentView property to this custom view.
add three labels as sub viewsinto uitableview cell's content.then assign apprrpriate values to it
eg:
- (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] autorelease];
}
//frame should be set accordingly(means should be framed accordingly).
UILabel *l1=[[UILabel alloc]initWithFrame:CGRectMake(5, 5, 100,100)];
UILabel *l2=[[UILabel alloc]initWithFrame:CGRectMake(110,10,100,80)];
UILabel *l3=[[UILabel alloc]initWithFrame:CGRectMake(115,60,100,50)];
[cell.contentView addSubview:l1];
[cell.contentView addSubview:l2];
[cell.contentView addSubview:l3];
return cell;
}