I have Custom uitableviewcell: ScrollViewCell
I want to know what the difference is between the following code
static NSString *CellIdentifier = #"ScrollViewCell";
ScrollViewCell *cell = (ScrollViewCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
//***** WHAT IS THE DIFFERENCE BETWEEN THIS CODE AND..
NSArray *xibObj = [[NSBundle mainBundle] loadNibNamed:#"ScrollViewCell" owner:nil options:nil];
for(id currentObj in xibObj){
if ([currentObj isKindOfClass:[ScrollViewCell class]]) {
cell = (ScrollViewCell *) currentObj;
}
}
//***** ..THIS CODE
cell = [[ScrollViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
Which one should I use and why?
The first example will load a cell from a .xib file in your application's bundle. Each cell can handle it's own code, and behaves a lot like a UIViewController. This approach can get complicated when you try and load data from an array. You have to pass the object you're getting data out of to the cell, and have a very clear design before you start coding.
The other method allocates an empty instance of the UITableViewCell class as normal. This approach is typically used for programmatic configuration of the cells. You'll probably see this one in most places.
Good luck,
Aurum Aquila
Related
Currently I have the following method, but it doesn't quite work...
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *MyIdentifier = #"cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil) {
[[NSBundle mainBundle] loadNibNamed:#"TVCell" owner:self options:nil];
cell = tvCell;
self.tvCell = nil;
}
UILabel *label;
label = (UILabel *)[cell viewWithTag:5];
label.text = [NSString stringWithFormat:#"Hole #%d", indexPath.row];
return cell;
}
The table view gets created with no errors, but each individual cell contains nothing, but clearly the TVCell.xib has a label with a tag of 5. The only question I have is this. I don't quite understand these steps apple gives here...
Select File’s Owner in the nib document window, open the Identity pane of the inspector, and set the class of File’s Owner to your custom view controller class.
Connect the cell outlet of File’s Owner (now the placeholder instance of your custom subclass) to the table-view cell object in the nib-file document.
Here is where those steps are...
http://developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/TableView_iPhone/TableViewCells/TableViewCells.html#//apple_ref/doc/uid/TP40007451-CH7
Can someone please explain those steps for a noob like me? I think that is what I messed up on, but I could have done anything wrong.
I don't think TcCell becomes a property of self. Try this instead when the cell queue is empty:
if (cell == nil) {
cell=[[NSBundle mainBundle] loadNibNamed:#"TVCell" owner:self options:nil];
}
It's kind of difficult to explain the steps that you said you don't understand in words. I would suggest looking for tutorials that have images or videos for that. (I did a quick search and there are lots available, but I didn't really want to choose one to direct you to without having read them more closely).
However, I prefer to create custom table view cells this way:
http://www.mobilesce.com/2011/12/27/the-best-way-to-do-custom-reusable-uitableviewcells/
It's slightly different from the way described in the apple docs, but I've seen a lot of people use it and I find it easier.
The NSBundle method loadNibNamed:owner:options: returns an NSArray containing the top level objects in your nib file. Try this:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil) {
NSArray *nibArray = [[NSBundle mainBundle] loadNibNamed:#"TVCell" owner:self options:nil];
cell = [nibArray objectAtIndex:0];
}
I taken a custom cell and i am not reusing the identifier over there. I am using the identifier in the table view where i am using that custom cells. But when i run my application and entering the data in textfield my data getting erased when i scroll the view.and My cell are not reusing that data.Can any one help me out in this thing. Thanks!
Custom cell code
-(UITableViewCell *)returnCellForEach:(UITableView *)tableView
{
[[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil];
myLabel = (UILabel *)[customCell.contentView viewWithTag:10];
return customCell;
}
Table view 'cellForRowAtIndexPath' code
static NSString *CellIdentifier = #"Cell";
cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:#"Hello"] autorelease];
}
whats mistake i this thing. Thanks!
Cells should not be used to store your data. If the user enters something in the edit field, you need to copy the content to e.g. a member variable in your view controller. If the cell is scrolled out of view, it is either destroyed, or it MIGHT be kept for reuse. Either way, you can not rely on that edit field to exist anymore.
I dont get your question actually, But I have done like following :
cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
cell = (CustomCell *)[[[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil] objectAtIndex:0];
}
myLabel = (UILabel *)[customCell.contentView viewWithTag:10];
//myLabel = cell.labelWithTag10;
myLable.text = #"Text";
And It works fine for me;
I have an array which I am using to furnish the contents of custom cell in table view
I dont know whats wrong but when I scroll a tableview the contants oc cell changes dynamically
Please help me to fix this
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *MyIdentifier = #"MyIdentifier";
MyIdentifier = #"tblCellView";
NSString *offendersImagePath = [self applicationDocumentsDirectory];
//NSLog(#"%#", dbPath);
offendersImagePath=[offendersImagePath stringByAppendingPathComponent:#"Images"];
CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if(cell == nil) {
[[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil];
cell = aCustomCell;
aCustomCell=nil;
}
NSMutableArray *tempArray;//=[[NSMutableDictionary alloc] init];
tempArray=[offendersNamesList objectAtIndex:indexPath.row];
//NSLog(#"%d",indexPath.row);
offendersImagePath=[offendersImagePath stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.jpg",[tempArray objectAtIndex:0]]];
NSLog(offendersImagePath);
[[cell offendersImageView] setImage:[UIImage imageWithContentsOfFile:offendersImagePath]];
[cell.offendersNameLbl setText:[tempArray objectAtIndex:1]];
[cell.offendersViolation setText:[tempArray objectAtIndex:2]];
//[tempDictionary release];
//[cell setLabelText:[arryData objectAtIndex:indexPath.row]];
return cell;
}
What is typically the problem in these kinds of problems is that you are not setting up the content in your cell correctly in the cellForRowAtIndexPath. When a cell scrolls off the screen the system dumps it into a "Recycle Queue" (my term). As new cells scroll onto the screen the system looks in this recycle queue for cells it can reuse.
((CustomCell *)[tableView dequeueReusableCellWithIdentifier:MyIdentifier];)
If it does not find one it goes ahead and builds an entirely new one from scratch. In your case, it looks like for whatever reason you are not setting up the cell content correctly and the changes you are seeing are recycled cells that have not been updated with the correct content.
I'm not sure exactly where you are going wrong but the code you are using for new cells is a little strange. It should look more like this:
if(cell == nil) {
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil];
cell = [nib objectAtIndex:0];
}
I'm not 100% what your issue is, but if it's items that have variable text length and the items on the cell aren't getting re-sized, it's because the sizings of the labels contained in the cell are not getting updated, just their text is getting changed.
A note about doing lookups in the cellForRowAtIndexPath, perhaps you should construct your array(of objects/dictionaries) in viewDidLoad, so as to be more efficient.
Another thing to note is your using .jpg files. It's more optimal to use .png files as they are crushed in size at compile time.
Also using NSMutableArray *tempArray; and hard-coded indexes is very bad practice, if something changes position in the array it means you have to change all your code. Try using a NSDictionary so as the keys are less likely to change.
I am trying to build a custom table view using a cell that I built in IB. I am getting a strange error:
<BroadcastViewController 0x4b4f5f0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key postText.
Everything is wired up correctly in IB to the cell controller. Not really sure why this is happening.
This is what my cellForRowAtIndexPath looks like:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
//Get the folder object of interest
Broadcast *messageAtIndex = [self.messages objectAtIndex:indexPath.row] ;
static NSString *CellIdentifier = #"BroadcastTableViewCell";
static NSString *CellNib = #"BroadcastTableViewCell";
BroadcastTableViewCell *cell = (BroadcastTableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
//ERRORING ON THIS LINE...
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:CellNib owner:self options:nil];
cell = (BroadcastTableViewCell *)[nib objectAtIndex:0];
}
cell.postText.text = messageAtIndex.replyText;
cell.authorName.text = messageAtIndex.postCreatorFirstName;
cell.postDate.text = messageAtIndex.creationDate;
return cell;
}
Anyone seen this kind of error before? Let me know if you need any more information...
What is really strange is that it complains that the class BroadcastViewController is not KVC compliant to postText.
As far as I can see, postText is a label in your cell, so the IBOutlet for this should be in the BroadcastTableViewCell class. So check out where you've linked the postText label in IB. Also, it can be that you had an IBOutlet in your view controller for this label, you've removed it but you forgot to delete the link in IB. Anyway, there somewhere is your problem. The fact that you have the error on that line is just because it's there you load your NIB, it doesn't have anything to do with the cell itself or with the owner.
Might has something to do with dequeueReusableCellWithIdentifier returning an UITableViewCell*.
I normaly do this:
UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier...
CustomCell* acell = (CustomCell*)cell;
Set the owner to nil.
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:CellNib owner:nil options:nil];
Ok figured it out. The connections in IB were indeed incorrect. I had them linked to the file's owner as opposed to the actual objects. I am going to give this too Stelian because he directed me to check out the nib. Thanks for all your help!
I am building a simple Navigation-based app using tables.
I have a custom "UITableViewCell" to customize the table cell data attached below.
#interface NewsCell : UITableViewCell
{
IBOutlet UILabel *newsTitle;
}
- (void)setNewsLabel:(NSString *)title;
#end
And then in my RootViewController, I set the text of the label "newsTitle" in "cellForRowAtIndexPath" method as follows.
static NSString *MyIdentifier = #"MyIdentifier";
MyIdentifier = #"NewsCell";
NewsCell *cell = (NewsCell *)[tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if(cell == nil)
{
[[NSBundle mainBundle] loadNibNamed:#"NewsCell" owner:self options:nil];
cell = newsCell;
}
[cell setNewsLabel:#"hello testing"];
return cell;
When I run this, the app runs fine, but I get "NewsCell may not respond to '-setNewsLabel:'" warning.
Please help! Thank you.
In RootViewController.m, you need to `#import "NewsCell.h".
Or, stick #import "NewsCell.h" in your project's PCH (pre-compiled header) file.
The underlying issue is that the compiler only knows about methods that it has previously seen when parsing the header files (or ones in the PCH).
You're creating the nib, but not assigning it to anything. See this question to create it right.
Where does the variable newsCell come from? Is it really of type NewsCell?