I need to edit the position of an UITableViewCell programmatically, this is the relevant code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"leftMenuCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] ;
}
if([[[self.arForTable objectAtIndex:indexPath.row] valueForKey:#"level"] intValue] == 1)
{
CGRect frame = cell.textLabel.frame;
frame.origin.x= 30;
cell.textLabel.frame= frame;
}
return cell;
}
Using breakpoints I can see that the if condition works but the code to edit the frame position does nothing. Is it possible to edit the position like this or i'll have to subclass UITableViewCell?
I think you should create 2 subclasses of UITableViewCell with 2 different identifiers depending on the one you want to display if they are different.
You could customize frame in each subclass as you want and it will be easier for you to work with it
Related
Here's where the magic isn't happening:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"songCell";
songViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
// Configure the cell...
long row = indexPath.row;
if (cell == nil) {
cell = [[songViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
if (tableView == self.searchDisplayController.searchResultsTableView) {
cell.songLabel.text = _searchResults[row];
} else {
cell.songLabel.text = _songListArray[row];
}
return cell;
}
I know the _searchResults array is populated with the correct search results and I've edited the numberOfRowsPerSection appropriately. The filter is working correctly, but it won't display the _searchResults[row] text while typing into the search bar. If I don't use the bar, the cells are populated correctly with _songListArray[row].
Something is going wrong in:
if (cell == nil) {
cell = [[songViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
If I don't include the if expression, I get an error. How should I initialize the prototype cell while the search bar is in use? All I get is empty labels, but I know the search is working because if there are no filtered results in the array the table says "No Results" in the middle. Why isn't my songLabel.text updating?? It won't even display text when I set the label to #"HELLO??" instead of the array[row].
You need to have the searchResultsTableView dequeue a cell, not just your main table view. The cellForRowAtIndexPath method should look something like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
if (tableView == self.tableView) {
RDTriangleCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
cell.textLabel.text = self.theData[indexPath.row];
return cell;
}else{
UITableViewCell *cell = [self.searchDisplayController.searchResultsTableView dequeueReusableCellWithIdentifier:#"SearchCell" forIndexPath:indexPath];
//RDCell *cell = [self.searchDisplayController.searchResultsTableView dequeueReusableCellWithIdentifier:#"SearchCell" forIndexPath:indexPath];
cell.textLabel.text = self.filteredData[indexPath.row];
return cell;
}
}
In viewDidLoad, you should register the class if you use the code I show above for a standard UITableViewCell.
[self.searchDisplayController.searchResultsTableView registerClass:[UITableViewCell class] forCellReuseIdentifier:#"SearchCell"];
If you use a custom cell for the search results table, then you should use something like the line I have commented out, and register the nib for that custom cell.
As a Xcode beginner, I want to display a thumbnail in the table cell in my app. For now, I have this code which parses JSON data and posts it in the title and subtitle of the cell.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"MainCell"];
if(cell == nil){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:#"MainCell"];
}
cell.textLabel.text = [[news objectAtIndex:indexPath.row] objectForKey:#"receta"];
cell.detailTextLabel.text = [[news objectAtIndex:indexPath.row] objectForKey:#"koha"];
return cell;
}
How can I show a thumbnail in the right of the cell?
Thanks.
If you don't want to make a custom cell, you can create a UIImageView with your desired image and set it as the cell's accessoryView, which will show it on the right edge of the cell. You also need to ensure that the height of the cell is tall enough to fit the image's height.
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
return 100;
}
- (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];
}
cell.accessoryView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"some-image-name"]];
return cell;
}
You can return a constant (I chose 100) if the image will always be a fixed size, or you can check the UIImage's size and return something like size.height + 10 for some extra padding.
I'm trying to add a data source inside a UITableView. I tried the following, but unfortunately it didn't work:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 8;
}
// Customize the appearance of table view cells.
- (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];
}
// Set the data for this cell:
cell.textLabel.text = [_classCellview objectAtIndex:indexPath.row];
cell.detailTextLabel.text = #"One";
cell.detailTextLabel.text = #"Two";
// set the accessory view:
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
return cell;
}
cell.textLabel.text = [_classCellview objectAtIndex:indexPath.row];
You're telling the table that there are 8 sections, but you're not taking the section from the index path into account when you populate the cell. An index path has (in the case of a table view) two values: a section and a row. You need them both to know what cell you're dealing with. So, you're probably getting the same content repeated in each section of your table. (It'd help if you told us exactly what the problem is, though.)
Okay, I am having another UITableView problem. For some reason the indexPath.row is all jumbled up. When I comment out the if statement that sets up the cell, everything works fine. The NSLogs tell me that they are loading in order, but all the cells are out of order.
It also seems as if they repeat; I only see 8 cells, and they repeat over and over.
Here's my code:
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
NSLog(#"row: %d",indexPath.row);
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
cell.backgroundColor = [UIColor clearColor];
cell.contentView.backgroundColor = [UIColor clearColor];
// Add subviews like this:
// [[cell contentView] addSubview:objectName];
// And I get the row number like this: indexPath.row when getting objects from the array
}
return cell;
}
To use your code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
NSLog(#"row: %d",indexPath.row);
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
cell.backgroundColor = [UIColor clearColor];
cell.contentView.backgroundColor = [UIColor clearColor];
// Add subviews like this:
// [[cell contentView] addSubview:objectName];
}
### Move this here ###
// And I get the row number like this: indexPath.row when getting objects from the array
return cell;
}
" I only see 8 cells, and they repeat over and over." Correct.
What your missing is that that is how it is supposed to work. That's why only if the cell is nil are you alloc & init'ing a new cell. So you alloc and init and set the colors and add subviews in the if statement. Then after the if(cell==nil) you know you have a valid cell to populate with some data according to the indexPath variable passed in.
The problem is that now you are setting up the cell when it is nil and assigning all of the displayed data according to the indexPath passed in. The problem is cell is not nil the second time it's used so the data is never changed.
To address your speed comment further, I'll use an old fallback example.
- (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];
UILabel *hugeLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, cell.frame.size.width, cell.frame.size.height)];
hugeLabel.tag = 300;
[cell addSubview:hugeLabel];
}
[(UILabel *)[cell viewWithTag:300] setText:[arrayOfStrings objectAtIndex:indexPath.row]];
return cell;
}
If you look at the sample above, you'll see that we add a UILabel to the cell setting it's tag to 300. Then after the if statement we will have either a brand new cell or a reused cell with text already in the label. No matter either way we simply change the text of the existing label to whatever it should be considering the row. In this way we avoid creating views over and over.
If you are dead-set on caching your UITableViewCells you could do so like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.row < _cells.count){
return [_cells objectAtIndex:indexPath.row]; // _cells is an NSMutableArray setup in viewDidLoad
}
UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#""];
cell.textLabel.text = [source objectAtIndex:indexPath.row]; // source is an NSArray of NSStrings I set up in viewDidLoad
[_cells addObject:cell];
return cell;
}
Note When running this on device don't be surprised when in the console you see Received memory warning What's efficient & what's easy are often not the same.
The way you have it set up now, cell.selectionStyle, cell.backgroundColor, and cell.contentView.backgrounColor, etc., only get set when if (cell == nil) is true. You need to move that code outside the if statement block, so that it gets called both when dequeueReusableCellWithIdentifier: produces a cell and when it has no cells in inventory and produces nothing (i.e., nil).
I was debugging an issue with a view controller recently and noticed that each time I drag the view up or down it will repaint the entire contents of my UITableView (as it calls the cellForRowAtIndexPath method each time). Is it possible to use an in memory datasource or add another delegate to my view controller so it won't repaint each time?
I'm not modifying anything inside the cells when the user interacts with it so my data source would be static after the initial "viewDidLoad" is called.
- (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] autorelease];
}
if ([self.hats count] > 0) {
//do some complex stuff in here that hurts each time we re-draw this ...
}
return cell;
}
Thank you in advance
so // complex stuff means adding UIViews.
I make an example for an UIImageView. Since you don't show the complex stuff you have to adopt it on your own.
your code looks like this:
- (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] autorelease];
}
if ([self.hats count] > 0) {
UIImageView *imageView = [[UIImageView....];
[cell.contentView addSubView:imageView];
[imageView setImage:foo];
[imageView release];
}
return cell;
}
refactor your code that it looks like this:
- (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] autorelease];
UIImageView *imageView = [[UIImageView....];
[cell.contentView addSubView:imageView];
imageView.tag = 42;
[imageView release];
}
if ([self.hats count] > 0) {
UIImageView *imageView = [cell viewWithTag:42];
[imageView setImage:foo];
}
return cell;
}
et voila, your tableview is responsive. Because you create the subviews exactly one time for each cell. And when the cell isn't used anymore and goes into the reuse bin the subviews stay with it.
And if you need 4 imageViews in one cell and 8 in another, you add 8 imageviews when you create the cell and give them a frame of CGRectZero and of course a different tag for each view.
If you need them you show them, if you don't need them you set the image to nil and the frame to zero.