tl;dr: Can I cause the detailTextLabel to have its size updated by the auto layout system in iOS on a value change?
Has anyone else had issues with the detailText label within an UITableViewCell since iOS 8?
I have a table which both text and detail strings. Initially detail text is an empty string (#""). After performing a storyboard segue to an edit screen, I return with a new value for the detail text and update it. I attempt to reload the table in viewWillAppear so that the value is present immediately upon returning to the previous view.
Once the table view is visible again, the table cell has shifted the text field up to make room for the detail text, but no detail text is displayed. The text does not display until I return to the edit screen, and come back a second time.
What I've done to troubleshoot: It looks as thought the auto layout for the detail text label isn't correctly updating as I think it should, and logging the size and makeup of the detailTextLabel's frame confirms this.
I am able to force the text to update by running [table reloadData] within viewDidAppear, however that leaves me with a flicker effect I don't like, and looks unprofessional.
Edit: Additional things I've done: I've also forced the detailTextLabel to re-size itself using [cell.detailTextLabel sizeToFit]. This causes it to display, but offset in an odd way in the cell. After going to the edit page again, the detailTextLabel fixes it's position.
I've created a simple project as a github repo, to show exactly what I'm dealing with:
https://github.com/acidaris/ios8_table_issue
The main code of the view controller I'm using is also below.
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[self.table reloadData];
}
- (NSInteger)tableView:(UITableView *)tableView
numberOfRowsInSection:(NSInteger)section {
return 1;
}
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:#"CellIdentifier"];
cell.textLabel.text = #"This is a test";
cell.detailTextLabel.text = self.value;
CGRect frame = cell.detailTextLabel.frame;
NSLog(#"detailTextLabel x=%f y=%f width=%f height=%f",
frame.origin.x,frame.origin.y,frame.size.width,frame.size.height);
return cell;
}
The cell is prototyped within a StoryBoard, and so the cell selected by dequeueReusableCellWithIdentifier: is always defined. Additionally, the cell type within the storyboard is set to subtitle, and it does display if the initial value is defined.
If anyone could help me figure this out, I would be incredibly grateful.
Partial Solution
If you are sub-classing UITableViewCell, you can modify the frame for the detailTextLabel when the layout is done. This is what I've done, and it seems to have worked, but on the 6 plus, I get a weird dividing line between the textLabel and the detailTextLabel. edit: (I have adjusted for this.) I don't like this solution, but thus far it's the best I've come across. It doesn't update after presenting the view, and is relatively simple. As I said above, I will continue to look for a better solution.
- (void)layoutSubviews {
[super layoutSubviews];
CGRect textFrame = self.textLabel.frame;
[self.detailTextLabel sizeToFit];
CGFloat x = textFrame.origin.x;
CGFloat y = textFrame.origin.y + textFrame.size.height;
CGSize detailSize = self.detailTextLabel.frame.size;
CGRect newFrame = CGRectMake(x, y, detailSize.width, detailSize.height);
self.detailTextLabel.frame = newFrame;
}
I've also updated my Github project to reflect my current solution. Edit3: This doesn't work perfectly, as it has wrong values for truly auto layout frames, but it works for my uses for the moment.
Edit 4: I've updated my layoutSubviews function to be smarter. It will size to fix the content within the label, and position the label appropriately within the x/y coordinates in relation to the text label.
Having the same problem. My solution was to call [cell layoutSubviews] before returning the cell at the end of -tableView:cellFForRowAtIndexPath. This works for me, and I didn't find it necessary to override layoutSubviews in the cell subclass.
I have same problem with cell not updating correctly when using segue in storyboard.
Tried
[setNeedsLayout] and [layoutIfNeeded]
on the view and the tableview and it is NOT working.
[self.tableView reloadData] is in viewDidAppear, as it should.
Then I tried the advice from pixbug, and it worked. But one should NOT use [layoutSubviews] directly. So I tried the ones that is adviced by the documents on the cell instead of tableView or the view.
Tried
[cell setNeedsLayout]
but this did NOT work.
Tried
[cell layoutIfNeeded]
this WORKED for me.
I put this before returning the cell.
I had the same problem in an iOS 8 storyboard (without Auto Layout enabled).
I had a Table View with a static Table View Cell at the bottom of it. In IB, I added some spaces into that table cell's content area (Style: "Right Detail"). Then in code (ViewDidLoad), I updated that cell's content with...
self.copyrightsCell.detailTextLabel.text = #"<a string>";
WITHOUT the IB spaces, the cell was INVISIBLE in portrait mode.
But WITH the initial spaces, the cell's content later appears correctly.
Hope this helps someone.
I have the same issue.
I have am certain that the data is available and being assigned to the cell.detailTextLabel.text
I have noticed that once a value has been assigned then there is no flicker if the value is changed on the return to the tableView.
So it appears to me that there is only an issue on the first assignment of a value to the detailTextLabel.
So, I followed this tread and many others. This one lead me to what seems to be the correct answer. I hope this helps others, since this has driven me crazy since iOS 7 / 8 made some sort of changes.
My answer was to put the normal processing code in viewWillAppear and add this [self.tableview layoutSubviews] instead of [self.tableView reload data]. I think this has to do with Apple making things much more controllable in iOS 7 / 8. I struck upon that idea when reviewing some info on how cells were working.
Again, I hope this helps others resolve this annoying problem.
I had a similar problem with a static UITableView. I change a label's text and it doesn't get updated on the screen unless I clicked on the cell or did anything to force update its views.
My workaround was to call after updating the text:
tableView.reloadData()
P.S This doesn't make any sense; because this is a static table view, and I don't know why it worked, but it did!
I think that if you need to reloadData, that means that the table data isn't loaded when its created.
You'd just need to load your data in the viewdidload (or somewhere else BEFORE the table view gets its data ) where your tableview is, and then create the cells accordingly.
Usually, i just use an array of whatever object i'm using and then use [array objectAtIndex:indexpath.row], which you probably know about.
Also, you ante-last paragraph has an unfinished sentence that looks important.
Confirming the problem using Xcode 6.3.2 (6D2105) OS X Yosemite 10.10.3
I made sure that the correct value was being assigned, still first time no show,
second time show.
cell.layoutSubviews() seemed logical to me since it appeared as if the view lacked a refresh and adding layoutSubviews() did the trick.
Related
My setup
I have a UITableViewCell that is in my main storyboard in a UITableViewController. It gets populated with some JSON data pulled from a REST API that will cause each cell to be a variable height. There are UIImageViews, UILabels all of different heights and styles, think Instagram-esque.
My problem
When I scroll to maybe the 5th or 6th cell, then go back up, they start redrawing and overlapping, so text gets mixed, lines get redrawn, etc.
What I've tried
This seems like a common problem on SO, so I've tried several posted solutions. It seems like my issue is probably the same problem as others face, which is, I am calling addSubview on my cell every time it dequeues, but I've tried checking to see if the cell already exists. I came across another post somewhere (sorry, I can't remember where), that suggests that because I am creating this in the storyboard, it is already initialized and if ( !cell ) will already return false, so I don't know how to prevent it from redrawing.
When I try removing the cell from the storyboard, and creating it programmatically, I get an error saying it can't find a cell with my identifier #"Cell".
I've also tried someone's solution of removing all subviews when I dequeue, so I used:
for ( UIView *view in cell.contentView.subviews ) {
if ([view isKindOfClass:[UIView class]]) {
[view removeFromSuperview];
}
}
and it doesn't find anything.
#rdelmar's comment is correct. You shouldn't do what you're doing. Might work, but it's bad form and you don't want to get into bad habits.
First, take advantage of object oriented programming. A cell should be able to configure itself based on the data you ask it to display. The table view shouldn't be designing the cell.
UITableViewCells need to be optimized for speed. Creating and adding subviews is a slow process. It's OK to do it once, but the cell will be reused (a system optimization) and you should just reuse the existing views that were added the first time the cell was created.
For example, you can hide subviews if they're not needed. You might want to do this in -prepareForReuse. You can move them around in -layoutSubviews. Or change the position of subviews in -updateConstraints.
Typically you just want to pass the data to display to the table view cell subclass from the data source (often the view controller). Let the cell do the display work.
When you add your subview after dequeueing uour cell, give a tag to your subview. This way, when you dequeue a cell, you can first check for the presence of a subview with your tag, and if it exists, remove it before adding your new view:
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
...
// try to dequeue a cell
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:<yourCellIdentifier>];
if( !cell )
{
// create a new cell if necessary
}
static int _myViewTag = 1000987 // give it a high int : low value are used by the system in cells
UIView *v = cell.contentView viewWithTag:_myViewTag];
if( v ) // subview with such tag already exists, so remove it.
[v removeFromSuperview];
// now add your new subview
[cell.contentView addSubview:<yourView>];
// adjust height of cell to your view.
...
}
Try to add a new method in your cell class to reset cell to its default style and call this method after dequeueCell.
The most efficient way to manage this is to subclass UITableViewCell and adding all your required Views as properties. So now when a cell comes up for "recycling", you know where to find the old views, like :
[cell.myTextLabel setText:#""];
aaaand you're done.
UPDATE creating a subclass makes sense if you have only a small number of "TYPES" of cells. create a subclass for each. How much complicated it gets depends on your specific scenario. But i've done it and found it to be the most effective method.
UPDATE 2 or you could make multiple cells in the storyboard, and dequeue the appropriate one based on the data source, save all the coding.
I've got a UITableView, each cell has an image and two labels, as you can see on the first picture
So I am trying ti use self-sizing cells and everything is great, except 2 things:
1) First and Second cell don't show content properly, but after I scroll down and then return to them everything is ok. I tried to use [tableview reloadData] in viewDidAppear, but it doesn't help. Watch the labels at first they don't fit. You can watch it on this video https://www.youtube.com/watch?v=I9DGBl1c5vg
Look at the labels on the first cell.
2) It's a tough one. I'm scrolling the table and everything is great, but the problem happens, when I select the row. It's pushing me to detail view, but when I press "back" and return to master view, the tableview jumps,so I'm coming back not to the selected row, also if I scroll the table it doesn't scroll smooth, but jumps. Here are the links for two videos, first one shows that scroll is smooth https://www.youtube.com/watch?v=9wAICcZwfO4 if i don't go to detail view, and the second shows the jumping problem https://www.youtube.com/watch?v=fRcQ3Za1wDM .
It's absolutely sure connected with self sizing cells, because if I don't use it, none of this problem happens.
Okay, I solved both of the problems.
Question 1
I've added these two lines
[cell.contentView setNeedsLayout];
[cell.contentView layoutIfNeeded];
in
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath before return cell
Question 2
The solution appeared to be very simple. I've just needed to implement viewWillDissapear and reload data in it, so the code looks like this
- (void)viewWillDisappear:(BOOL)animated;{
[super viewWillDisappear:animated];
[self.tableView reloadData];
}
Solution for me was simple, if it doesn't work for someone, here I found some useful links.
1) UITableView layout messing up on push segue and return. (iOS 8, Xcode beta 5, Swift)
2) http://useyourloaf.com/blog/2014/08/07/self-sizing-table-view-cells.html
Unfortunately I believe both of the questions that you ask about are IOS bugs.
Question (1)
A easy fix is suggested by this blog.
When the table view is first displayed, you may find some of the cells are not sized properly. But when you scroll the table view, the new cells are displayed with correct row height. To workaround this issue, you can force a reload after the view appears:
Simply add the following to your viewDidAppear method. I have tested it and it works very well.
[self.tableView reloadData];
Question (2)
This second question is a duplicate of this following question:
IOS 8 UITableView self-sizing cells jump/shift visually when a new view controller is pushed
A workaround is suggested by the author of the question himself, which seems okay. However, I have not tried out this one yet.
Okay, I solved it by caching my cell heights in sizeThatFits, and returning that value for estimated cell heights within the delegate. Works beautifully.
Feel free to head over to that question for other proposed solutions.
I would like to implement a UITableView with cells that are full screen. When the user moves the cell up a portion, I would like to jump to the next cell as opposed to allowing it to scroll naturally.
I can't see a great deal of questions or answers out there on this, and perhaps it's because it's a daft idea, but the client wants to see it and the designer has designed it as such so I really must try.
Does anyone have ANY suggestions on how to implement this?
Thanks. (and thanks for pointing out my ignorance in not saying thanks!)
If your cells are going to be the same size as your tableView's height, set the pagingEnabled property to YES. This will make it snap to a full cell on each vertical swipe. I would ensure that the height is exactly full-screen if you do this, otherwise you'll end up with some weird offsets as you scroll.
- (void)viewDidLoad
{
[super viewDidLoad];
// or somewhere similar
self.tableView.pagingEnabled = YES;
}
...
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return self.tableView.frame.size.height;
}
It actually isn't a terrible idea- you could achieve similar functionality with a paging scroll-view, but this has the advantage of not needing to have all of your data loaded at once.
Edit: I also had to make sure to disable automaticallyAdjustsScrollViewInsets on the controller, otherwise I had an undesired initial offset for the first cell, just in case you run in to that as well.
Before I get crucified for this, let me state... Yes, I have read every "relevant" answer on this topic and have not found a workable solution. Most "correct" answers are pre-ARC and discuss "releasing" a cell, which just isn't done anymore. Secondly, my problem is not "global", meaning some views have no problems, while others do. So here is my question...
I have sub-classed uitableviewcell and setup some uilabels & custom uiviews. From there I wired everything up in ib (Xcode 5.x iOS 7.x). Once I put in the appropriate code and create the tableview & dynamic cells from a nsarray "not mutable" everything works exactly as expected with no issues.
This is the fun part. I am making changes to allow the data source of the tableview, which is an nsarray to be mutable to allow adding and removing of items / cells. This is where things get hairy. When I start to add more objects to the array and when the reuse cell is being put on screen visual data from old cells is being reused on new cells. I say "visual" because once the cell is selected the view updates to display the correct information. The part that is interesting is that as I stated I have some uilabels which never have any problems being redisplayed, my custom views however are now the piece of the puzzle that is displaying info from past cells, and when scrolling back up, the original cells no longer display the correct information. Once the cell is tapped, then the cell updates and displays the correct information.
the most confusing bit of this is that before my array was mutable and had a static amount of objects this worked fine. Even if a cell went off screen and came back, it was still the correct information being displayed. Now I know that shouldn't have anything to do with it, but it is strange that it worked using the same tableview & cell code that I am using now.
I have tried adding in
MyCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
if (!cell) {
cell = [[MyCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"Cell"]; // note: obviously as stated, tacking on "autorelease" here as mention in other suggestions is not going to work.
}
Which doesn't fix the issue.
I tried overriding the "prepareForReuse" method on my custom cell subclass and that does not resolve the issue either. I have made the views, "strong" & "weak", and all that and still every 3rd or so cell gets repeated with garbage data until it is refreshed. Again, the uilabels which are setup the same way as the views have no problems and data is never reused. I would say there is a problem with my custom views, but setting up the table from a static source of identical information there is no problem.
I would like to post some code, but it's all pretty generic code for tableviews & delegates. any suggestions would be greatly appreciated.
As i said the code is all pretty generic, but apparently it needs posing anyway so here it is..
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
MyThing *thing = self.stuffArray[indexPath.row];
MyCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
cell.thisLabel.text = thing.someText;
cell.thatLabel.text = thing.otherText;
cell.view1.someProptery = thing.object1.property
cell.view2.someProptery = thing.object2.property
cell.view3.someProptery = thing.object3.property
//"someProperty" on "view..." is an NSInt that is used to determine custom drawing in the view.
return cell;
}
I think the key to the solution lies in your comment about the custom views in the cells. If cellForRowAtIndexPath is altering the states of those views, they need to know that they must be redrawn, so you'll need to augment the synthesized setter in your custom view.m that has someProperty.
If the someProperty determines how this view get's drawn, then it's incumbent upon the setter to indicate that the view is out of date....
- (void)setSomeProperty:(NSInteger)someInt {
_someProperty = someInt;
[self setNeedsDisplay];
}
I have a problem that is driving me crazy.
I have an UITableView that is always in editing mode (it has to be).
The user can add new rows to it.
The navigationItem.leftbarButton of the tableViewController pushes a new controller just to do it, let's call it "newRowsVC".
Before the push the tableViewController set itself as the delegate of the newRowsVC, the protocol has only a method:
-(void) aNewRowHasBeenCreated
{
[self.tableView reloadData];
}
I start adding rows and everything works fine, each now row is immediately displayed in the tableViewController until the last new row will force the tableView to scroll because there won't be anymore screen real estate for it. Here, I have no idea why, the tableView, only it, is as frozen, with no scrollbar and doesn't respond to input. The app continues to run without a crash and I can even dismiss the tableViewController by tapping the navigationItem.rightbarButtonItem.
I can keep creating new rows, they are added to the array, the number of row in the tableView data source is computed correctly. But the table is like dead.
If I dismiss the tableViewController and then I come back to it, I see that all the rows previously created, also the ones not shown as soon as they were created are there!
I really do not have idea of how I can fix this.
The first thing I tried was to force the scroll after the reload of the table but it didn't fix it.
-(void) aNewRowHasBeenCreated
{
[self.tableView reloadData];
[self.tableView setScrollEnabled:YES];
}
I also tried forcing the tableView to scroll to the last row but it didn't fix it.
-(void) aNewRowHasBeenCreated
{
[self.tableView reloadData];
[self.tableView setScrollEnabled: YES];
[self.tableView scrollToRowAtIndexPosition: [self.tableView indexPathsForVisibleRows]last object] atScrollPosition: UITableViewScrollPositionBottom animated:YES];
}
I check the number of rows each time the table is reloaded. No error, the number is perfect and the new rows data are correctly in the array, also the data for the cells not shown.
I thought it could be because the tableView is always in editing mode so I tried setting it to NO but nothing changes, id din't fix the problem.
Two notes:
1)the tableView has to be the delegate of each one of it's custom cells. They have an UITextField and an UIStepper, handled by the tableViewController. I already tried to not set the tableViewController as the delegate of its custom cells but nothing changes so the problem is not this.
2) self.tableView.bounces = NO but this has nothing to do with the scrolling issue, the scroll is enabled.
Update: After more tests I found that if I remove the dequeue of the reusable custom cell everything works fine, so the problem should be about the reuse.
static NSString *CellIdentifier=#"MyCell"
CustomCell *cell = [tableView dequeueReusableCellWithIdentifier: CellIdentifier];
Nicola
After hours I got it. As pointed out by Amit the problem was hidden in cellForRowAtIndexPath... It was hard to catch because it didn't happened all the times and the first times I enabled/disabled the cell reusing everything seemed the same so I did not link the problem to it. I got back on it after I tried about all the other options I had been able to think about.
The problem was in the reuse of the cells and the fact that the custom cell has the tableView as its delegate to handle its textView and the stepper without exposing them.
I got rid of all the delagion stuff and exposed the textView and the stepper as public properties of the view. By doing this I was able to set the tableViewController directly to be the delegate of the cell.textView and to add directly a target/action for the stepper.
Everything works flawslessly now.
Thanks to everyone who tried to help me!
Nicola