When I write a simple code to create a table, I got _CGRect referenced From error. I don't know how to solve this error. I even added the CoreGraphics framework into my project
static NSString *SimpleTableIdentifier = #"SimpleTableIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: SimpleTableIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier: SimpleTableIdentifier] autorelease];
}
NSUInteger row = [indexPath row];
cell.text = [listData objectAtIndex:row];
return cell;
try
CGRectMake(0,0,widthOfCell,heightOfCell)
in your
cell initWithFrame
method, i think tht should do it for you.
Related
I am new in iPhone development. I am using UItableview for showing list.
And able to show all items successfully.
But they changed when I scroll tableview.
Please help me.
Try this code in cellForRowAtIndexPath method of tableview
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
Please give me more information to show your case clearly.
Have a look at this function first because all rows are generated from here!
(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *simpleTableIdentifier = #"SimpleTableCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:simpleTableIdentifier];
}
cell.textLabel.text = [recipes objectAtIndex:indexPath.row];
return cell;
}
Check whether each row is exist,unless just reuse it later.
Can anyone please tell me what is the correct way to manage UITableView if I have a big number of cells? The interface of each cell depends on sections (each cell keeps different UI elements in its content view). I do not want to use reusable cells as it messes up with overlapping.
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault nil] autorelease];
} else {
cell = nil;
[cell release];
cell = [[[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault nil] autorelease];
}
No, your code is not correct. First of all, it wouldn't even compile because [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault nil] is not valid syntax. Secondly, the [cell release]; line has no effect (which is good because if it had, it would be wrong) but its presence shows that you haven't understood the memory management concepts (yet).
Thirdly and most importantly, you should definitely use the table view's cell reuse, especially if you have a big table. If you have different types of cells, just use different reuse identifiers for them, no problem. The table view will then create multiple reuse pools and always return a cell of the type you ask it for in dequeueReusableCellWithIdentifier:.
I'm using reusable cells in my app. The method I'm using is as follows:
-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"CellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
NSUInteger row = [indexPath row];
cell.textLabel.text = [yourArray objectAtIndex:row];
return cell;
}
It works fine.
Without reuseIdentfier you will run out of memory fast and tableview will scroll slow. You should change content of cells in this method, e.g. titles, images, etc. but not views. So create subclasses of cell for every section you need. Setup their views and in this method setup content.
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier] autorelease];
} else {
cell.title = [_cellTitles objectAtIndex:indexPath.row];
cell.image = [_cellImages objectAtIndex:indexPath.section];
}
I have a list of cells in a table view where only the last cell has a disclosure indicator (it triggers an action). When I scroll down my list of cells everything works fine, but if I scroll back up oddly the disclosure indicator appears in other cells too. I can't really figure out where's the problem, any help?
Thanks,
Daniele
This is the part of code that is use:
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
cell.textLabel.text = [myArray objectAtIndex:indexPath.row];
if(([myArray count]-1) == indexPath.row) {
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
that is not a bug: it is a feature ;) because the cells are being reused.
If your tableview contains 200 cells and your iphone is able to show 5 cells at the same time then you only have 5-6 instances of UITableViewCell. If you scroll down a cell gets the disclosure-button and if you scroll back the cell is being reused and as a result the disclosure-button is still there.
to solve your problem:
approach 1: not only set the disclosure-button on the last cell. you should also remove/unset it in other cells.
approach 2: it seems that the last cell is another type of cell in semantic. So choose a reuse-identifier for example: #"MyLastCell for the last cell and #"MyCell" for all other cells. As a result your tableview will only reuse cells of the same type (in your case: with/without disclosure-button)
edit 1: some sample-pseudo-code for approach 2 ;
edit 3: shorter solution for approach 2
static NSString *CellIdentifier = #"Cell";
static NSString *LastCellIdentifier = #"LastCell";
bool isLastRow = (indexPath.row == numRows-1);
NSString *usedCellIdentifier = isLastRow ? LastCellIdentifier : CellIdentifier;
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: usedCellIdentifier];
if(!cell)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:usedCellIdentifier] autorelease];
if(isLastCell)
{
//do disclosure-stuff here. Or add a UIButton here
cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton
}
}
edit 2: sample code for approach 1
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
cell.accessoryType = (idexPath.row == numRows-1) ?
UITableViewCellAccessoryDetailDisclosureButton
: UITableViewCellAccessoryNone ;
As thomas said, you can use his code and you can add this:
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
for the last cell (inside the if where you dequeue your last cell) and this:
cell.accessoryType = UITableViewCellAccessoryNone;
for other cells (inside the if where you dequeue other cells).
I haven't tried this code but it should work... ;)
try this
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
cell.textLabel.text = [myArray objectAtIndex:indexPath.row];
if(([myArray count]-1) == indexPath.row) {
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
else{
cell.accessoryType = UITableViewCellAccessoryNone;
}
iPhone/iPad SimpleTableViewCells: What replaces the deprecated setImage setText on table cells?
The below code gives warnings that setImage and setText are deprecated. So what replaced them? What is the new better way to get this simple behavior?
static NSString *SimpleTableIdentifier = #"SimpleTableIdentifier";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier: SimpleTableIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero
reuseIdentifier: SimpleTableIdentifier] autorelease];
}
cell.image=[UIImage imageNamed:#"Wazoo.png"];;
cell.text = #"Wazoo";
So what is the simplest way to have the same affect as image/text of a cell without doing a lot of work or getting warnings?
With new release of iOS SDK, setText and setImage properties are deprecated and they are replaced by textLabel.text for setText and imageView.image for setImage...
With this new properties, your code would be:
static NSString *SimpleTableIdentifier = #"SimpleTableIdentifier";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier: SimpleTableIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero
reuseIdentifier: SimpleTableIdentifier] autorelease];
}
cell.imageView.image = [UIImage imageNamed:#"Wazoo.png"];;
cell.textLabel.text = #"Wazoo";
This properties are usually used when the cell uses preimpostated styles like UITableViewCellStyleDefault, UITableViewCellStyleSubtitle, UITableViewCellStyleValue1 and UITableViewCellStyleValue2 or CGRect...
If you will display also a subtitle, the code to be used is:
cell.detailTextLabel.text = #"Your Subtitle Here!";
You call textLabel.text and imageView.image on the cell.
static NSString *SimpleTableIdentifier = #"SimpleTableIdentifier";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier: SimpleTableIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero
reuseIdentifier: SimpleTableIdentifier] autorelease];
}
cell.imageView.image=[UIImage imageNamed:#"Wazoo.png"];;
cell.textLabel.text = #"Wazoo";
I am having a problem with my code skipping over the if(cell == nil) after about nine trips through the cellForRowAtIndexPath. Then items in my table start repeating and do so every nine items. When I remove the if(cell == nil) line, the table comes out beautifully, with all the data in the right order. However, if I scroll to the bottom of the table, my app crashes so that is not a good solution. Any ideas please??
Thank you!
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier] autorelease];
NSString *temp = [[views objectAtIndex:indexPath.row] objectForKey:#"racer"];
NSString *val = [[views objectAtIndex:indexPath.row] objectForKey:#"pointsScored"];
// Set up the cell...
cell.textLabel.text = temp;
cell.textLabel.font = [UIFont boldSystemFontOfSize:15];
cell.detailTextLabel.text = val;
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
[temp release];
[val release];
}
return cell;
}
KLevSki,
That is because you are re-using tableview cells via dequeueReusableCellWithIdentifier which is a good thing on the iPhone platform. What happens is this:
1) Cell is created in the if (cell==nil) section
2) Once a number of cells are created (in your case 9 of them, based roughly on how many are shown on screen), the OS begins to re-use the table cells to be a good memory manager instead of creating a unique table cell for each and every row which could be memory intensive
3) Since the cell is being re-used, all you need to do in the section after the if (cell==nil) block is to update/change the information on each cell.
As an example... If you created a cell that had only an icon and a label on it, each time the cell is scrolled into view, you would update the icon and label to whatever image/string is appropriate for that cell.
For your case:
...
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier] autorelease];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
// update cell
cell.textLabel.text = [[views objectAtIndex:indexPath.row] objectForKey:#"racer"];
cell.textLabel.font = [UIFont boldSystemFontOfSize:15];
cell.detailTextLabel.text = [[views objectAtIndex:indexPath.row] objectForKey:#"pointsScored"];
return cell;