Here is my code :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *cellIdentifier=#"menucell";
MenuCell *cell = (MenuCell*) [tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];
if (cell==nil)
cell= [[MenuCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier] ;
MenuModel *resturntent = (self.menuList)[indexPath.row];
cell.foodNameLbl.text = resturntent.MenuName;
cell.priceLbl.text = [NSString stringWithFormat:#"%# %#",#"$" , resturntent.MenuRate];
cell.foodImage.image = [UIImage imageNamed:#"full_breakfast.jpg"];
return cell;
}
While scrolling uitextfields values gets duplicates .
I need help to fix this issues
When you use dequeueReusableCellWithIdentifier, your cells will be reused. This means when the user scrolls the tableview, a cell which moves out of the screen will be reused to display the contents of a cell which is about to move onto the screen.
Even though this helps in saving memory, the problem it causes is the that the cell needs to be prepared for display before it is loaded with the content of the new cell.
In your case, it seems you need to maintain the values the user has entered in a textfield of a cell.
So to fix your problem, if there are not that many cells in the tableview, simply stop reusing the cell. Else whenever the user enters a value in the textfield of a cell, save it in an array (array of 'MenuModel' in your case). And fetch the value from from the model and set it to your textfield in the cellForRowAtIndexPath method like your have set values for other labels.
Related
I am trying to implement rating stars by using kDRATING VIEW .i have used following code in cellForRowAtIndexpath method but it causes my app to become slower.
If it try to allocate and initialise this in viewdidload method then it when i scroll up and down ,the stars fluctuates . please help in this regard
self.rating = [[KDRatingView alloc] initWithFrame:CGRectMake(0, 0, 60,20)];
[self.rating rateKDRatingView:2.80 outOf:3.0];
[cell.rating addSubview:self.rating ];
return cell;
It sounds like you need to look into UITableViewCell reuse because when you scroll a UITableViewCell out of the screen it will call cellForRowAtIndexPath again to remake this cell when it is back in view and that can cause flickering and memory consumption.
You are adding the KDRatingView to the rating view on the cell so I guess you have a custom cell, so why not instead have the KDRatingView inside the custom cell and just update its value when you need to.
Try this solution with some cell reuse:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"RatingCell";
RatingCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil){
// initialisation code
cell = [RatingCell new];
}
// setting code
[cell setRatingViewValue:2.8 outOf:3.0];
}
That way it only creates the cell once, so it won't slow down your app. Then each time the cell would have been recreated it just updates the cells rating (and anything else you need to set) instead.
Then you just need to implement the setRatingViewValue:outOf: method in your custom cell to update the KDRatingView that you need to have added and positioned in your custom cell upon initialisation.
So I've created a TableView as below, but I have quite an annoying problem.
When I come to this VC, I click Choose User, and I selected user Atoshum.
When I scroll down, this top cell goes off screen as I scroll through the bottom cells.
When I scroll back up, the cell has reverted to a default (or occasionally, takes the value of another cell).
I make the cells as such.
static NSString *CellIdentifier = #"Cell";
DMSDrugInstanceCell *Cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (!Cell) {
Cell = [[DMSDrugInstanceCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
Cell.chooseUserButton.tag = indexPath.row;
[Cell.chooseUserButton addTarget:self
action:#selector(performSegue:)
forControlEvents:UIControlEventTouchUpInside];
return Cell;
In the cell creation you dont ever set any values. All you do is set the tag and then add an event target. If you want it to keep the choose, you need to store/save that choice when it is made and then in the cell create, set it based on that saved value.
you are reusing table cell. So every time your cell reload then you need to set value in cell.
in cellForRowAtIndexPath method , you need to set value in cell according to index path.
This is because the UITableView do not create the new cells for total number of elements. Rather it re-uses the cells which are off the visibility. Hence you feel that your data is reset or getting reflected on some other cell.
The best approach is to store all your data in some Array (let it be tagDataArray) and then set your cells as
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
DMSDrugInstanceCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[DMSDrugInstanceCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
Cell.chooseUserButton.tag = [tagDataArray objectAtIndex:indexPath.row];
...
...
return Cell;
}
I'm using a custom UITableViewCell subclass, called MessageCell.
I initialise the cell like so:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
MessageCell *cell = [tableView dequeueReusableCellWithIdentifier:#"messageCell"];
// more code
return cell;
}
In each custom cell I have a checkbox used to mark this cell. When a cell is marked it is being added to an array, and vice versa.
While this works in terms of data, the UI is not reflecting it as it should. What happens is that in addition to the marked cell, other cells are being marked.
I assume this behaviour stems from cell reusability, i.e when I mark a cell as selected it has a common pointer with all future cells in this screen position.
For this reason, I want to use "normal" non-reusable cells.
So I tried:
MessageCell *cell = [[MessageCell alloc] init];
OR:
MessageCell *cell = [[MessageCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil];
But both of them resulted in displaying empty cells.
You still want to reuse cells! Just check your data and set the checkbox to checked or unchecked in your cellForRowAtIndexPath:
MessageCell *cell = [tableView dequeueReusableCellWithIdentifier: #"messageCell"];
if (condition cell should be checked) //set the cells checkbox to checked
else //set the cells checkbox to unchecked
Or some approach like that.
PS on re-reading your question:
do you really need a reference to a cell in your array? Can't you for example store the indexPath and use cellForRowAtIndexPath: if you need to make a cell out of it?
I have a UITable which shows the 10 most recent images from a web service. Each row has its own image. When the UITable first loads in the viewcontroller it doesnt show the first 4 images in the rows (screen is blank). If I scroll down the last 6 images appear....then if I scroll back the first 4 images that were NOT there originally DO appear and everything looks the way I wanted it to initially. My guess is its something do with the way cells are reused.
Here is my tableView code:
- (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.selectionStyle = UITableViewCellSelectionStyleBlue;
}
[cell.contentView.subviews makeObjectsPerformSelector:#selector(removeFromSuperview)];
[cell.contentView addSubview:[self.photoList objectAtIndex:indexPath.row]];
return cell;
}
What solved my issue was adding the following line to my method that deals with streaming the photos from the Web API:
[_tableView reloadData];
I noticed that if I moved the Table View Cell up or down in the its Table View at the Storyboard that changed the position of the invisible row as well. So I solved the problem by setting the Table View Cell as hidden.
I have a UITableViewController with UITextfield inside the tableview cells. If I scroll the table view, the user entered data in the textfields disappears. I tried to add the textfield data to a NSMutableArray but it still didn't work. Any help please.
When cellForRowAtIndexPath: is called, the cell you return has to be completely filled in with whatever data you want to show. So, if the cell includes a UITextfield, you'll need to set it's text property to the right value for that row in your data.
When a table cell disappears off the top or bottom of the screen, the UITableViewCell itself becomes available for re-use. (As you scroll, cells disappear, and new cells appear, but the UITableView class is re-using the UITableViewCell objects.) In cellForRowAtIndexPath: when you get a cached cell to use, you have to be sure to setup everything you want it to show for the row in question, otherwise you might see some odd behavior in your table.
Does this help?
EDIT:
Here's an example of the typical pattern used in cellForRowAtIndexPath:. Notice the use of dequeueReusableCellWithIdentifier:. That method returns a previously allocated but not in use UITableViewCell, if there is one. Notice further that if no cached cell is returned, the code creates a new one, and sets it up (with stuff that is independent of anything that might be row specific). Following that, you'd setup the cell as you need it for the row in question.
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *SearchResultsCellIdentifier = #"SearchResultsCellIdentifer";
UITableViewCell *cell = [tableView
dequeueReusableCellWithIdentifier:SearchResultsCellIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
reuseIdentifier:SearchResultsCellIdentifier] autorelease];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
// Your row-specific setup of the cell here
// ...
return cell;
}
Check the docs for specifics about these methods. There are LOTS of examples from Apple and elsewhere about how to implement tableViews.