I am implementing UITableViewDelegate and UITableViewDataSource in my VC.
I have this code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:
(NSIndexPath *) indexPath {
// do stuff
if(condition){
cell.textLabel.backgroundColor = [UIColor redColor];
}
else {
cell.textLabel.backgroundColor = [UIColor blackColor];
}
}
Pretty standard stuff. The issue I am running into is that the first set of visible cells has no coloring. If I scroll to cells that aren't visible, I get correctly colored cells. If I scroll back, I the cells are colored.
I understand that the cells are 'created' and 'destroyed' as needed, which explains some of it, I just doesn't understand why cellForRowAtIndexPath, which is fired before I see anything, and my coloring conditionals being hit, results in... no coloring.
A work around is to iterate through the visible cells after calling reloadData on the table view, I am just hoping there is an easier way.
Dane
Cell coloring needs to be done in the tableView:willDisplayCell:forRowAtIndexPath: delegate method, not the tableView:cellForRowAtIndexPath: method.
Remove any cell coloring logic from the tableView:cellForRowAtIndexPath: method and move it to the tableView:willDisplayCell:forRowAtIndexPath: method.
Related
I receive a color from the server and in cellForRowAtIndexPath method I'm trying to apply this color to a view inside the cell.
The problem is that all the cells display the same color until I scroll down the table. When I start scrolling they update well their color.
I'm new on iOS and Objective-C, so if you could help me it would be appreciated, thanks.
Before scrolling:
After scrolling:
Some code: (If you want more please tell me)
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
CalendarDayCell *cell = (CalendarDayCell *) [tableView dequeueReusableCellWithIdentifier:#"CalendarDayCell"];
if (cell == nil) {
cell = [[CalendarDayCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"CalendarDayCell"];
}
if (self.events.count) {
CalendarEvent *ce = self.events[indexPath.row];
CalendarDayCell *dayCell = (CalendarDayCell *) cell;
// ...
dayCell.viewColorBar.backgroundColor = [self colorWithHexString:ce.color];
return dayCell;
} else {
// Not important
}
}
PS: I've also tried it at willDisplayCell method with the same results.
EDIT:
Finally I figured out what were the solutions.
IDK why XCode redimensioned the color bar height to be 980px from the 50px that I specified in the nib file. And that was causing that all cells below had the same color.
I put all the views in another view, and assigned that view to the cell because some cells were not showing their color.
that's all
The problem is with reusing the cells - that means that in cellForRowAtIndex path you have to set color for every condition. This is easily reproducible with images. If you set image only sometimes, you will have to set image to none when you don't need to display it. What you need to do is to handle in the else block the control you want to change.
if(self.events.count){
dayCell.viewColorBar.backgroundColor = [self colorWithHexString:ce.color];
}
else{
dayCell.viewColorBar.backgroundColor = [UIColor clearColor];
}
Or something like that.
Are you sure that self.events.count is actually non-zero? Perhaps the tableview is being populated before self.events is setup properly.
For example, the view controller might be loading via viewDidLoad, then the UITableView, then you're setting self.events. If that's the case, self.events will be nil until the whole view/viewcontroller is loaded. That would account for it working after you start scrolling.
I changed the color of text for the cell clicked in the table. But after the cell is clicked, when i come back to table the text of cell has the original color. Could you give me an advice?
This is the code in "didSelectRowAtIndexPath"
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
cell.textLabel.highlightedTextColor = [UIColor blueColor];
Thank you
after the cell is clicked, when i come back to table the text of cell has the original color. Could you give me an advice?
You need to have the color for each cell stored somewhere other than in the table, so that you can reproduce the colors you want anytime the table redraws itself. Typically, you'll have some sort of data structure that stores the table's data, and that's usually the right place to save any changes the user makes. The table view's data source should have a -tableView:cellForRowAtIndexPath: method that sets the color according to what you've saved, along with any other cell attributes.
This is happen because the cells are reused, so lets say when you change text colour property of some cell it will be affected as you expect but when you scroll and that cell disappear off the screen it will be put to reuse pool and if it appears again on the screen table view takes some cell from the reuse pool but it's properties will be different so the colour won't persist.
You should keep somewhere, for example in NSMutableArray, info about which table was clicked.
You can add an index path to the array when you click the cell and in cellForRowAtIndexPath: check is this indexPath in the array and if it is change appropriate property.
The problem is that iOS throws away your cell if you scroll away and recreates it when it's needed (you scroll back to the cell).
If I were you, I would subclass UITableViewCell and overwrite
- (void)setSelected:(BOOL)selected animated:(BOOL)animated;
In there you would have
- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
[super setSelected: selected animated: animated];
self.textLabel.textColor = selected ? [UIColor blueColor] : [UIColor blackColor];
}
Since iOS UITableView remembers which cell is selected, this should work fine, even when it's recreated.
The reason it's happening is what others are saying: cells are reused.
Storing selection state or color will work, however if you just need to make sure that selected cells have a different color for a label than non-selected cells, there's a way that does not require to use a supporting data structure.
You just need to check if the cell being setup at - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath is currently selected or not, and that can be achieved with [tableView indexPathForSelectedRow] if your table uses single selection, or [tableView indexPathsForSelectedRows] if it uses multiple selection.
The last case requires you to find the current indexPath in the returned array, and might be slower than using the supporting array.
But if the selection is simple, then this solution is probably faster, uses less memory and is easier to read (IMO).
The table view I have changes Cell background colors quite often. The colors set in -(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath are fine but some colors are set after the table view loads like:
- (void) ChangeCellColorAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:currentCell inSection:0]];
cell.backgroundView.backgroundColor = [UIColor orangeColor];
}
If a cell is changed with that method it will revert back to what it was originally set to when it scrolls out of view. How can I insure it will stay the same color when I scroll out of view.
You should take into account how the cell loading process works: when you set the color of a visible cell and the user scrolls to a point where that cell is not visible, and then scrolls back to the original point the table view will call again tableView:cellForRowAtIndexPath:, a new cell will be created(better said an already created cell will be reused if you are doing things correctly as I assume) and the background color you previously set will be ignored.
The solution is to know which color each cell should have in tableView:cellForRowAtIndexPath: and set the color there.
I need to do something like this :
.
Is it a UITableView? Or how should I do this? Any idea is welcome.
Code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.section == 0) {
if (indexPath.row == 0) return cell1;
} else if (indexPath.section == 1) {
if (indexPath.row == 0) return cell2;
} else if (indexPath.section == 2) {
if (indexPath.row == 0) return cell3;
}
}
Most likely its a UITableView. May be its not (it can be a UIScrollView with views added like sections in a table view).
But if you want to create something like in the image, I'd suggest you to use UITableView with customized cells. Because implementing table view, in this case, is simpler as you have to just concern about the delegate and the dateSource of the table view, rather than worrying about aligning the views in order.
Use sectioned table view with the translucent, gray-bordered, black-background-view as the backgroundView of the cells. Add the labels and arrow as the subviews of cell. You can add arrow as the accessoryView but that would become vertically centered, but in the image the arrow is displayed slightly on top of the cell.
There should be only one cell in each section.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return 1;
}
There can be any number of sections (3 here).
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 3; // Can be any number
}
Yes, that's most likely a styled table view. See this guide or this nice tutorial.
why you worry about this one? Its simple man.... its nothing ,if you have hands over UITableView. Yeah, You must know about :
1: Set background image on view,exact as table size.
2: Set table view onto them and make background transparent.
3: Make customize table cell and add to table' row.
Thats it.....enjoy this work..its a creativity.
And you can do it guy....
I cannot tell exactly what is used from the picture, however I suggest using the UITableView especially if you have variable data coming from a structured object.
Some tutorials which I found very useful are the following:
Creating customized UITableViewCell from XIB
http://www.bdunagan.com/2009/06/28/custom-uitableviewcell-from-a-xib-in-interface-builder/
UIViewTable anti-patterns - A very good MVC pattern to build UIViewTable
http://www.slideshare.net/nullobject/uitableviewcontroller-antipatterns
And of course Apple's docs:
http:/developer.apple.com/library/ios/#DOCUMENTATION/UserExperience/Conceptual/TableView_iPhone/TableViewCells/TableViewCells.html
One important fact to remember is that you should always reuse cached table cells through the datasource method tableView:didSelectRowAtIndexPath:
Note: Since you want lots of transparencies there might be some performance issue especially on older devices.
Hope this helps and goodluck with your project.
There is not need to its scrollview or tableview... both are perform same..
Just change the Background Color of Tableview as clear color.....
check this code...
put this line to viewDidLoad :
[tableView setBackgroundColor:[UIColor clearColor]];
and
(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
..... // Your label buttons etc........
......
......
.....
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
[cell setClipsToBounds:YES];
[[cell layer] setBorderColor:[[UIColor blackColor] CGColor]];
[[cell layer] setCornerRadius:10];
}
You can do this using tableView in
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 1;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
//here place return your array contents
}
We can accomplish the similar as shown in image above by Table View and scroll view both.If you don't want to use table view then you can take a scroll view or a simple view and can add several buttons along with the image in background with different frames.It means button background will have the same image.then you can use different labels to show all the texts in different labels according to the requirement.
OR
you can use table view.For this you need to return number of sections 3(in this image) in the delegate method - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView.and then everything as the default tableview style.And then change the cell style to detailed.
yes this is a tableView with custom UITableViewCell.you can do that by creating a empty xib file and then add a UITableViewCell and do your customizing ...then in cellForRowAtIndexPath method use:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:edentifier];
if (cell == nil) {
cell = [[[NSBundle mainBundle]loadNibNamed:#"yourCellName" owner:self options:nil]objectAtIndex:0];
this is from my application.
Yes, it is a groupedtableview with clearcolor as backgroundcolor. Cell background color also needs to be changed to clearcolor.
I suggest using div or list, don't use table, its very hard to control if the contents are too long.
I have a full list that populates a UITableView. This I want to background the one of the cells with a different color and it works initially, but for some reason when I start scrolling the table up and down, it starts drawing more cells with the green background.
Please note that there is always one detailCell.detailTimeLabel.text that's equal to currentTime.
The code I have is:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
... SOME MORE CODE HERE ...
if ([detailCell.detailTimeLabel.text isEqualToString:currentTime]) {
UIView* backgroundView = [[[UIView alloc] initWithFrame:CGRectZero] autorelease];
backgroundView.backgroundColor = [UIColor greenColor];
detailCell.backgroundView = backgroundView;
for (UIView* view in detailCell.contentView.subviews)
{
view.backgroundColor = [UIColor clearColor];
}
}
}
Which can be the problem?
Your trying to store data in a tableviewcell. You can't do this because the cells are constantly reused. The background you see repeated occurs because its the same cell being displayed over and over again with different text.
When you dequeue the cell, you need to reset it to blank and wipe out all the previous data. Then you should set the background color only if the data you are putting into the cell has the current time.
As a general rule, you should never refer to data in the cells. If you need to know what is in a particular cell, look at the data at the indexpath within the datamodel itself.