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.
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!
In this screen shot you can see that I have added UITableView in UIViewController then customized the UITableViewCell by adding some labels in it. But the issue is when I run the application. All of the cells are empty. There are no labels at all.
I am not getting what can be the issue. I have searched the web and read tutorials but couldn't resolve it.
I resolved this issue by myself, just after little effort.
Actually when you create a custom cell you have to do these things:
Setup the labels, images etc on storyboard cell.
Create a custom cell class (inheriting from UITableViewCell)(CustomCell.h & .m), CustomCell.h having all of the properties as iboutlet for labels, images etc. and synthesize them all in implementation.
After creating this custom class go back to storyboard, select the custom cell, change its class to the CustomCell and give it some identifier like "MyCustomCell", then right click on the custom cell and connect the IBOutlets with labels etc.
Now import CustomCell class in the class where you are implementing the UITableView and use the properties you defined in CustomCell class.
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *MyIdentifier = #"MyCustomCell";
CustomCell*cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:MyIdentifier] autorelease];
}
// Here we use the provided setImageWithURL: method to load the web image
// Ensure you use a placeholder image otherwise cells will be initialized with no image
[cell.imageView setImageWithURL:[NSURL URLWithString:#"http://example.com/image.jpg"]
placeholderImage:[UIImage imageNamed:#"placeholder"]];
cell.myCustomLabel.text = #"My Text";
return cell;
}
I did this all and my issue was resolved and please don't forget to connect the delegates & datasource and table.
Hope this will help others.
It is little bit late but you can solve your problem by setting the background color of your view as Clear Color from your storyboard.
in the tableview's delegate method , cellforrowatindexpath has a uitableviewcell inside it , there should be an identifier in the initialization of this cell. possibly it is "cell" or "cellIdentifier" .
you just need to select your cell from storyboard and enter this identifier string to the storyboard , where uitableviewcell's attribute inspector stays.
hope this helps.. :)
First Set cell identifier in storyboard #"Cell"
then set tag of label
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// Create
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] ;
}
UILabel *lblDate = (UILabel*)[cell viewWithTag:101];
UILabel *lblDistance = (UILabel*)[cell viewWithTag:102];
UILabel *lbltype = (UILabel*)[cell viewWithTag:103];
lblDate.text = [temp objectAtIndex:indexPath.row] valueForKey:#"date"] stringByReplacingOccurrencesOfString:#"-" withString:#"/"]];
lblDistance.text = [NSString stringWithFormat:#"%# KM",[[temp objectAtIndex:indexPath.row] valueForKey:#"distance"]];
NSString *type = [NSString stringWithFormat:#"%#",[[temp objectAtIndex:indexPath.row] valueForKey:#"distance"]];
if([type isEqualToString:#"0"])
{
lbltype.text = #"Personal";
}
else
{
lbltype.text = #"Bussiness";
}
// Configure
return cell;
}
I've used UIAppearance to set the background image of my table cells across my app.
[[UITableViewCell appearance] setBackgroundView:[ [UIImageView alloc] initWithImage:[ [UIImage imageNamed:#"list_bg.png"] stretchableImageWithLeftCapWidth:0.0 topCapHeight:5.0] ]];
However, when I view a list the background image is only set for one of the cells on screen. If I scroll the screen the background image is set on the cell that appears into view but it doesnt set this bg image on any other visible cell.
Anyone got any idea whats going on? I thought that by setting the UIAppearance of UITableviewCell that all instances of this type would automatically get the background image.
Thanks
Brian
Here is my cellForRowAtIndexPath method:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"plantCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
[[NSBundle mainBundle] loadNibNamed:#"PlantListCell" owner:self options:nil];
cell = _plantCell;
self.plantCell = nil;
}
Plant *plant = [self.fetchedResultsController objectAtIndexPath:indexPath];
UIImageView *thumbnail = (UIImageView *)[cell viewWithTag:1];
thumbnail.image = [UIImage imageNamed:[plant.name stringByAppendingString:#"_S"]];
UILabel *label = (UILabel *)[cell viewWithTag:2];
label.text = plant.name;
UIImageView *set = (UIImageView *)[cell viewWithTag:3];
set.image = [UIImage imageNamed:#"set"];
UIImageView *favourite = (UIImageView *)[cell viewWithTag:4];
favourite.image = [UIImage imageNamed:#"fav"];
return cell;
}
Yep. The issue with this is you're telling the UITableViewCell class to set the one UIImageView for each table view cell's background view. Once its set as one, its removed from its previous superview, and added to the new UITableViewCell. You're not getting duplicate UIImageViews set on each tableViewCell; you're getting the one view set on every table view cell.
So then its set and unset from each tableViewCell till the last one it was set on.
Using the appearance proxy for this method sets it on every object of the UITableViewCell.
I wouldn't use the appearance proxy to set the background view method, as whatever view you pass to it will be one view, which can only apply to one cell at a time.
My recommendation is to create a view for each cell independently, or creating a subclass which sets it on initialisation.
Thanks thebarcodeproject. It kind of makes sense alright, but I don't see why Apple bothered to allow us to set the UITableviewCell background image if it doesnt really work.
I went with a simple solution in the end by just setting the image in the cellForRowAtIndexPath method.
cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"list_bg.png"]];
It works fine, but not great if you have lots of tables and want to set it in a generic way.
Cheers
Brian
I solved this by creating a base class called CustomizableUITableCell and setting up a ui appearance value for the background image. Then whenever i create a cell that i need with a custom background i simple subclass CustomizableUITableCell.
//Header
#import <UIKit/UIKit.h>
#interface CustomizableUITableCell : UITableViewCell <UIAppearance>
#property (nonatomic, weak) UIColor *backgroundCellColor UI_APPEARANCE_SELECTOR;
#end
//Implementation
#import "CustomizableUITableCell.h"
#implementation CustomizableUITableCell
#synthesize backgroundCellColor;
#pragma mark - Public Methods.
-(void)setBackgroundCellColor:(UIColor *)backgroundColor
{
[super setBackgroundColor:backgroundColor];
}
#end
You can then set it using the appearance proxy.
[[CustomizableUITableCell appearance] setBackgroundCellColor:[UIColor colorWithPatternImage:backgroundImage]];
cell.backgroundView = [[UIImageView alloc]
initWithImage:[ [UIImage imageNamed:#"1.jpg"]
stretchableImageWithLeftCapWidth:0.0 topCapHeight:5.0] ];
It works for me..
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.
I have a table cell to which I'm adding subviews programmatically. All the textual subviews work fine, but I can't get an image subview working at all.
You'll notice that I set the background color to black. This is simply to indicate to me that the subview is indeed being initialized and positioned properly within the cell. When I remove the background color there is nothing there.
Also, the cell style is UITableViewCellStyleDefault but I don't think that's pertinent for custom subviews. I want the image positioned on the right, which is why I'm not using the standard imageView property that cells offer.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = (UITableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
// ... add textual views ...
UIImageView *img = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"clock.png"]];
img.frame = CGRectMake(271.0f, 10.0f, 19.0f, 22.0f);
img.backgroundColor = [UIColor blackColor];
[cell addSubview:img];
}
// ... more code ...
return cell;
}
Your code looks fine to an extent. One issue I had when I was creating my own UITableViewCells in code was I was creating the cells with variables like you are but you shouldn't do this.
What you should do is create the cell and then set the variables. If cells are different you should use different reuse identifiers. Hope this makes sense if not let me know and I'll update.