To get popovers in iOS7 to function properly it appears I have to make some workarounds, in the code below I'm trying to understand why redisplaying the popover the second time is necessary. Without the redisplay when in iOS7 the arrows point to the wrong place if they are turned on. Normally the app runs in landscape so I'm wondering if that has to do with orientation and timing of the animations. Also without the redisplay a transparent pane zooms out in about 500ms to fill the screen just before the popover slides into place. With the redisplay then the popover just snaps into the right place, as expected.
NSArray *currSysVer= [[UIDevice currentDevice].systemVersion componentsSeparatedByString:#"."];
if(self.showingKeyboard == NO) {
if([[currSysVer objectAtIndex:0] intValue] > 6)
{
[selectPopover presentPopoverFromRect:localField.frame inView:localField permittedArrowDirections:NO animated:NO];
}
else
{
[selectPopover presentPopoverFromRect:localField.frame inView:localField permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
}
}
//Determine height and width of popover to fit all values
CGFloat width = 320;
if(multiSelect) {
width = 450;
}
for(NSString *value in values) {
CGSize size = [value sizeWithFont:[UIFont systemFontOfSize:23]];
if(size.width > width) {
width = size.width;
}
}
CGFloat height = (44 * [values count] + 1) > 800 ? 800 : 44 * [values count] + 1;
if([[currSysVer objectAtIndex:0] intValue] > 6) {
height += 6;
}
[selectPopover setPopoverContentSize:CGSizeMake(width, height + 36) animated:NO];
if(self.showingKeyboard == NO && [[currSysVer objectAtIndex:0] intValue] > 6) {
[selectPopover presentPopoverFromRect:localField.frame inView:localField permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
}
I'm having the same issue, and can't really find a solution nor the reason. Maybe it's a bug, maybe not. Because for me it didnt matter too much if i presented popover horizontally or vertically, i used this workaround:
permittedArrowDirections:(UIPopoverArrowDirectionUp | UIPopoverArrowDirectionDown)
This way the popover wasnt floating around, and pointed to the right position.
Hope this helps to some.
I'm really struggling to understand why you're calling presentPopoverFromRect: before you call setPopoverContentSize:. I'm using UIPopoverController in my app, and I always set the content size before I display the popover.
Have you tried modifying your code so that you calculate the proper size for your popover - and then call setPopoverContentSize: - before you call presentPopoverFromRect:?
Related
There are some posts, where UIWebView bottom is black and can be resolved by two simple ways.
1. Clear Background of UIWebView
2. Set Opaque to NO.
However, this only solves problem for static UIWebView which is not changing its Frame or Constraints.
In my case, I have a UIWebView, It is very simple Drag and Drop on Storyboard's ViewController's View. No Inheritance. I set Background clear and set opaque to NO.
It looks fine up to now. But when I apply animation, using Facebook POP library
1. SetOpaque = YES, With Animation is clips the UIWebView's content showing black color.
2. SetOpaque = NO, With Animation is clips the UIWebView's content showing nothing (a View or something comes in front)
-(void) setConstraint {
_topConstraintValue = self.topConstraint.constant - 200;
NSLog(#"Value is UP %f " ,_topConstraintValue);
}
- (IBAction)animateUp:(UIButton *)sender {
[self setConstraint];
[VSAnimation popChangeConstraintForBasicAnimation:self.topConstraint begin:0.5 newConstant:_topConstraintValue withDuartion:0.5 isEaseInAnimation:NO withCompletionBlock:nil];
}
-(void) setConstraintDown {
_topConstraintValue = 0;
_topConstraintValue = self.topConstraint.constant;
NSLog(#"Value is Down %f " ,_topConstraintValue);
}
- (IBAction)animateDown:(UIButton *)sender {
[self setConstraintDown];
[VSAnimation popChangeConstraintForBasicAnimation:self.topConstraint begin:0.5 newConstant:[self getAnimatableConstraint:_topConstraintValue] withDuartion:0.5 isEaseInAnimation:NO withCompletionBlock:nil];
}
-(float)getAnimatableConstraint:(float)constant{
return constant+200.0;
}
-(float)getReverseAnimatableConstraint:(float)constant{
return constant-200.0;
}
Where, method inside VS is as below
//VSAnimation.m
+(void)popChangeConstraintForBasicAnimation:(NSLayoutConstraint *) layoutConstraintToPopChange begin:(float) beginTime newConstant:(CGFloat) newConstant withDuartion:(float)duration isEaseInAnimation:(BOOL)isEaseIn withCompletionBlock:(void (^)(POPAnimation *anim, BOOL finished)) completitionBlock{
NSString *key = [NSString stringWithFormat:#"constraints_changed_%#", layoutConstraintToPopChange];
POPBasicAnimation *basicAnim = [layoutConstraintToPopChange pop_animationForKey:key];
if(basicAnim){
basicAnim.toValue = #(newConstant);
basicAnim.completionBlock = completitionBlock;
}else{
basicAnim = [POPBasicAnimation animationWithPropertyNamed:kPOPLayoutConstraintConstant];
if(isEaseIn)
basicAnim.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
else
basicAnim.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
basicAnim.toValue = #(newConstant);
basicAnim.completionBlock = completitionBlock;
basicAnim.beginTime = [self timeWithDelay:beginTime];
basicAnim.delegate = self;
basicAnim.duration = duration;
[layoutConstraintToPopChange pop_addAnimation:basicAnim forKey:key];
}
}
What is this black line/transparent line at bottom.
How to stop this from increasing when one animates UIWebView.
IMAGES:
SHOWING ANIMATION UP & ANIMATION DOWN.
#VS, After reading you source code, I saw the constraint of the 2nd webview seems to be set wrongly. After I removed the height constraint WV2.height = 0.095 * height, the problem disappeared. You have to set the WV2's height constraint properly.
I've been looking at the same problem for so long I'm probably missing a simple solution here.
I created a small library to provide a custom UIView that sticks to the keyboard like the one for iMessage does (aka doesn't hide with keyboard): https://github.com/oseparovic/MessageComposerView
Basically the problem I'm experiencing is that when the user init's custom view I want a view with the following default rect initialized:
CGFloat defaultHeight = 44.0;
CGRect frame = CGRectMake(0,
[self currentScreenSize].height-defaultHeight,
[self currentScreenSize].width,
defaultHeight)
This requires that the currentScreenSize is calculated within the UIView. I've tried multiple implementations all of which have their downsides. There doesn't seems to be a good solution due to this breaking principles of MVC.
There are lots of duplicate questions on SO but most assume you have access to the rest of the code base (e.g. the app delegate) which this custom view does not so I'm looking for a self contained solution.
Here are the two leading implementations I'm using:
NextResponder
This solution seems to be fairly successful in a wide variety of scenarios. All it does is get the next responder's frame which very conveniently doesn't include the nav or status bar and can be used to position the UIView at the bottom of the screen.
The main problem is that self.nextResponder within the UIView is nil at the point of initialization, meaning it can't be used (at least not that I know) to set up the initial frame. Once the view has been initialized and added as a subview though this seems to work like a charm for various repositioning uses.
- (CGSize)currentScreenSize {
// return the screen size with respect to the orientation
return ((UIView*)self.nextResponder).frame.size;
}
ApplicationFrame
This was the solution I was using for a long time but it's far more bulky and has several problems. First of all, by using the applicationFrame you have to deal with the nav bar height as it will otherwise offset the position of your view. This means you have to determine if it is visible, get its height and subtract it from your currentSize.
Getting the nav bar unfortunately means you need to access the UINavigationController which is not nearly as simple as accessing the UIViewController. The best solution I've had so far is the below included currentNavigationBarHeight. I recently found an issue though where this will fail to get the nav bar height if a UIAlertView is present as [UIApplication sharedApplication].keyWindow.rootViewController will evaluate to _UIAlertShimPresentingViewController
- (CGSize)currentScreenSize {
// there are a few problems with this implementation. Namely nav bar height
// especially was unreliable. For example when UIAlertView height was present
// we couldn't properly determine the nav bar height. The above method appears to be
// working more consistently. If it doesn't work for you try this method below instead.
return [self currentScreenSizeInInterfaceOrientation:[self currentInterfaceOrientation]];
}
- (CGSize)currentScreenSizeInInterfaceOrientation:(UIInterfaceOrientation)orientation {
// http://stackoverflow.com/a/7905540/740474
// get the size of the application frame (screensize - status bar height)
CGSize size = [UIScreen mainScreen].applicationFrame.size;
// if the orientation at this point is landscape but it hasn't fully rotated yet use landscape size instead.
// handling differs between iOS 7 && 8 so need to check if size is properly configured or not. On
// iOS 7 height will still be greater than width in landscape without this call but on iOS 8
// it won't
if (UIInterfaceOrientationIsLandscape(orientation) && size.height > size.width) {
size = CGSizeMake(size.height, size.width);
}
// subtract the height of the navigation bar from the screen height
size.height -= [self currentNavigationBarHeight];
return size;
}
- (UIInterfaceOrientation)currentInterfaceOrientation {
// Returns the orientation of the Interface NOT the Device. The two do not happen in exact unison so
// this point is important.
return [UIApplication sharedApplication].statusBarOrientation;
}
- (CGFloat)currentNavigationBarHeight {
// TODO this will fail to get the correct height when a UIAlertView is present
id nav = [UIApplication sharedApplication].keyWindow.rootViewController;
if ([nav isKindOfClass:[UINavigationController class]]) {
UINavigationController *navc = (UINavigationController *) nav;
if(navc.navigationBarHidden) {
return 0;
} else {
return navc.navigationBar.frame.size.height;
}
}
return 0;
}
Does anyone have suggestion about how I can best calculate the UIViewController size from within this UIView. I'm totally open to other suggestions on how to stick the UIView to the bottom of the screen upon initialization that I may have overlooked. Thank you!
+ (id) getCurrentUIViewController : (id)res {
if([res isKindOfClass:[UIViewController class]]) {
return res;
}
else if ([res isKindOfClass:[UIView class]]) {
return [Function getCurrentUIViewController:[res nextResponder]];
}
else {
return nil;
}
}
I have a feed that gets populated with 15 posts from the server. When I scroll down to 3 before the end of the list, I ping the server for the next 15 posts. This functionality works great. However, when I start scrolling up, the UITableViewCells frequently jump up, as though Cell 5 is now populating Cell 4, and Cell 4 is now populating Cell 3, etc. Either that, or the UITableView scroll is just jumping up.
When I get to the very top of the UITableView and then proceed to scroll down through all my data then back up, it works perfectly though. Is there a drawing issue with my table?
Edit: So, I've come across the understanding that this is happening because the heights of all my cells are dynamic. I'm pretty sure as I'm scrolling up, my UITableView is calculating and setting the appropriate heights, which is causing the jumpy action. I'm not sure how to mitigate that.
I never used the new funcionality of dynamic cell size in iOS8, but I can give you few suggestion for improve performance on table views. It should be a comment but it doesn't fit.
Cache the height of cells already displayed if you can. It's easy an dictionary paired with a sort of id would do the trick
Pay attention that you do not have complex layout between subviews of you cells
Check if you are drawing something that requires offscreen rendering, such as corner radius, clipping etc
I don't know how dynamic cell works on ios8 but I share piece of my code. It's pretty straightforward. I have a cell that I use as prototype, each times I need to calculate a cell height I feed it with my data, that I force it's layout to get me the correct height. Once I've got the height I saved it in a NSDictionary using the postID(it's a twitter like app) as a key.
This happens only when the cell height is not cached. If it is cached the height is returned.
- (CGFloat) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
CGSize size = CGSizeZero;
NSDictionary * data = self.timelineData[indexPath.row];
if (data[KEY_CELL_IDENTIFIER] == CellIdentifierPost) {
NSNumber * cachedHeight = [self.heightCaches objectForKey:#([(AFTimelinePostObject*)data[KEY_CELL_DATA] hash])];//[(AFTimelinePostObject*)data[KEY_CELL_DATA] timelinePostObjectId]];
if (cachedHeight) {
return (CGFloat)[cachedHeight doubleValue];
}
[_heightCell configureCellWith:data[KEY_CELL_DATA]];
size = [_heightCell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
[self.heightCaches setObject:#(size.height) forKey:#([(AFTimelinePostObject*)data[KEY_CELL_DATA] hash])];//[(AFTimelinePostObject*)data[KEY_CELL_DATA] timelinePostObjectId]];
}
else if (data[KEY_CELL_IDENTIFIER] == CellIdentifierComment){
NSNumber * cachedHeight = [self.heightCaches objectForKey:#([(AFTimelinePostComments*)data[KEY_CELL_DATA] hash])];//[(AFTimelinePostObject*)data[KEY_CELL_DATA] timelinePostObjectId]];
if (cachedHeight) {
return (CGFloat)[cachedHeight doubleValue];
}
[_heightCommentCell configureCellWith:data[KEY_CELL_DATA]];
size = [_heightCommentCell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
if (size.height < 80.0f) {
size = (CGSize) {
.width = NSIntegerMax,
.height = 115.f
};
}
else if (size.height > 180.0f) {
size = (CGSize) {
.width = NSIntegerMax,
.height = 180.f
};
}
[self.heightCaches setObject:#(size.height) forKey:#([(AFTimelinePostComments*)data[KEY_CELL_DATA] hash])];//[(AFTimelinePostObject*)data[KEY_CELL_DATA] timelinePostObjectId]];
}
else {
size = (CGSize) {
.width = NSIntegerMax,
.height = 50.f
};
}
return size.height;
}
Unfortunately, there does not seem to be a simple answer to this. I have struggled with it on multiple iOS apps.
The only solution I have found is to programmatically scroll to the top of your UITableView once it appears again.
[self.tableView setContentOffset:CGPointMake(0, 0 - self.tableView.contentInset.top) animated:YES];
OR
self.tableView.contentOffset = CGPointMake(0, 0 - self.tableView.contentInset.top);
Hope this an acceptable work around while still being able to use dynamic cell heights =)
I'm working in a project (iOS7 & ARC) in which, I want to display N number of images in the scroll view.These Images already stored into sandbox directory. My App has only landscape orientation I'm facing a problem that ScrollView is not smooth, it stuck after 2-3 times scroll
This is how I configure ScrollView
[self.containerScroll setAutoresizesSubviews:NO];
self.containerScroll.pagingEnabled = YES;
self.containerScroll.showsHorizontalScrollIndicator = NO;
self.containerScroll.showsVerticalScrollIndicator = NO;
self.containerScroll.scrollsToTop = NO;
self.containerScroll.maximumZoomScale = 5.0;
self.containerScroll.minimumZoomScale = 1.0;
self.containerScroll.delegate = self;
I'm maintaining only three Images in the scrollView at a time.
I'm loading Images in ScrollView in below method
-(void) loadScrollViewWithPage:(int) page{
if (page >= self.numberOfSlides)
return;
float image_width;
float image_height;
if(self.isFromListView){
if(IS_IPHONE5){
image_width = 568.0f;
image_height = 320.0f;
} else{
// iPhone retina-3.5 inch
image_width = 480.0f;
image_height = 320.0f;
}
}
else{
image_width = IMAGE_WIDTH;
image_height = IMAGE_HEIGHT;
}
CGFloat xPos = page * image_width;
UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(xPos, 0.0f, image_width, image_height)];
imgView.tag = page;
NSString *imgPath = [self.storageDirPath stringByAppendingPathComponent:[NSString stringWithFormat:#"%d%#", page, Image_Extension_JPG]];
NSFileManager *fileManager = [NSFileManager defaultManager];
__block UIImage *img = nil;
if(![fileManager fileExistsAtPath:imgPath]){
[imgView setContentMode:UIViewContentModeCenter];
img = [UIImage imageNamed:#"icon-loader.png"];
[imgView setImage:img];
}
else{
[imgView setContentMode:UIViewContentModeScaleAspectFit];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
img = [[UIImage alloc] initWithCGImage:[[UIImage imageWithData:[NSData dataWithContentsOfFile:imgPath]] CGImage] scale:1.0 orientation:UIImageOrientationUp];
dispatch_async(dispatch_get_main_queue(), ^{
[imgView setImage:img];
});
});
}
[self.containerScroll addSubview:imgView];
img = nil;
fileManager = nil;
imgView = nil;
}
and this how my ScrollView Delegate methods goes...
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
self.containerScroll.scrollEnabled = YES;
float page = self.containerScroll.contentOffset.x/self.view.frame.size.width;
showingSlide = (UInt16) roundf(page);
if(scrollView == self.containerScroll){
// switch the indicator when more than 50% of the previous/next page is visible
CGFloat pageWidth = CGRectGetWidth(self.containerScroll.frame);
NSUInteger pageNo = floor((self.containerScroll.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling)
[self loadScrollViewWithPage:pageNo - 1];
[self loadScrollViewWithPage:pageNo];
[self loadScrollViewWithPage:pageNo + 1];
// a possible optimization would be to unload the views+controllers which are no longer visible
if(scrollView == self.containerScroll)
{
[self.previewTableView reloadData];
[self.previewTableView setContentOffset:CGPointMake(0, (page*220)+64) animated:NO];
[self.previewTableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:page inSection:0] atScrollPosition:UITableViewScrollPositionMiddle animated:YES];
[self updateSlideNumber];
[self flashSlideNumber];
}
//unload unnecessary imageviews from scroll view
for (UIView* view in self.containerScroll.subviews) {
if ([view isKindOfClass:[UIImageView class]] && view.tag != page && view.tag != page-1 && view.tag != page+1) {
[view removeFromSuperview];
}
}
}
}
Now the problem is smoothness of scrollView. When I start scrolling it scrolls fine but after 2 or 3 (or after any random number) pages scroll, it stuck and after trying 2-3 times only it moves again and I have to swipe hard to scroll. Thanks in advance.
I think it's a problem of memory somewhere Try #autorelease pool in your code.
using scrollview is not a good approach for showing images, I will recommend you to either use tableview or collevtionview for the same.
Your app's memory will keep on increasing with every scroll because scollview doesn't reuse the memory, on the other hand tableview and collectionview reuses the memory.
As the most effective way to become better, scroll really slowly (one at a time) while you monitor the memory usage in your App. You'll be able to watch it go up as each new image is added to the view, especially if you haven't done any optimisation on the images.
The other thing is that while your code does look like is deallocc-ing the images, you still need to remember that it still has to try to reload the images as you scroll. You're creating your images on the main thread so you're never going to get the smoothness of a UITableView. While I realise that you're creating your image views on async threads, the act of adding and scrolling them is still being taken care of by the mainthread.
I would suggest a UITableView to solve your problem, or a UICollectionView. If you're set on using the scrollview, I would suggest using a crusher of some type to get the image size to as small as possible, while still keeping quality decent.
If you need help on the TableView implementation you should find plenty of information around SO. Probably a good option if you still want it to look like a scroll view is just to make all seperators, headers etc to nil, and then just use lazy loading for the images.
You make two the mistake. At first: never use imageNamed for non graphics content (example, use imageNamed for button background). And second: you try load a big images in real time. So you scroll view have lags therefore. If you load all images before you show the scroll view the amination end lagging. But you can get memory warnings. So, you need optimise it. P.S. Sorry for my english
I have a popover screen, with inside it :
a label, that may or may not appear (title)
a search bar, that may or may not appear
a label, that may or may not appear, and has a variable height (help label)
a scrollview, that may or may not appear, and has a variable height (some infos about the following table)
a table view
In order to present something nice, in viewDidLoad, I move the various frames to place the objects correctly and not have unused spaces cluttering my popover. Besides, I then resize the table (to take the most place needed), and the popover via contentSizeInPopover (to avoid having a near-empty huge popover). All that resizing seems to work nicely, but I have one big problem : with all that resizing done, some cells of my UITableView become unresponsive. One or two cells, usually the second one, only respond if i tap in their outer corners, but the rest of the cell completely ignore any touches.
I've tried everything : moving all to viewWillAppear, letting the autoresize do its job (doesn't seem to work either), but I still have this problem every time. I've found that if I comment the lines involved with changing the frame of the table, or the ones in contentSizeInPopover, the problem stops, but then my view is messed up, so this ins't a fix.
If anyone could give me something to get out of this mess, that would be awesome.
- (CGFloat)getHeightWithoutTable {
return LIST_TITLE_HEIGHT + (self.searchBar.hidden ? 0 : LIST_SEARCH_BAR_HEIGHT) + (self.helpLabel.hidden ? 0 : self.helpLabel.frame.size.height + LIST_STD_SPACE) + (self.errorScrollView.hidden ? 0 : self.errorScrollView.frame.size.height + LIST_STD_SPACE);
}
-(void)viewDidLoad {
[super viewDidLoad];
self.tableViewOutlet.backgroundView = nil;
self.originData = [NSMutableArray array];
self.searchedData = [NSMutableArray array];
if (self.helper != nil) {
CGFloat heightOffset = 0;
// Content
self.originData = [self.helper getData];
self.tableData = [NSMutableArray arrayWithArray:self.originData];
// Title
NSString *title = [self.helper getPopoverTitle];
if (title == nil) {
self.popoverTitle.hidden = YES;
heightOffset -= LIST_TITLE_HEIGHT;
} else {
self.popoverTitle.text = [self.helper getPopoverTitle];
}
// Search
if ([self.originData count] [self getStdHeight] / 3){
self.helpLabel.lineBreakMode = UILineBreakModeTailTruncation;
[self.helpLabel sizeThatFits:CGSizeMake(self.helpLabel.frame.size.width, [self getStdHeight] / 3)];
}
heightOffset += (self.helpLabel.frame.size.height - LIST_HELP_STD_HEIGHT);
}
// Errors
if ([self.helper respondsToSelector:#selector(getErrors)]) {
self.errors = [self.helper getErrors];
}
if (self.errors == nil || [self.errors count] == 0) {
self.errorScrollView.hidden = YES;
self.errorBg.hidden = YES;
heightOffset -= LIST_ERROR_STD_HEIGHT + LIST_STD_SPACE;
} else {
[self createErrorView];
heightOffset += (self.errorScrollView.frame.size.height - LIST_ERROR_STD_HEIGHT);
}
// Table
CGFloat previewHeight = LIST_CELL_HEIGHT * [self.tableData count] + LIST_STD_SPACE;
CGFloat remainingHeight = LIST_MAX_HEIGHT - [self getHeightWithoutTable] - LIST_STD_SPACE;
CGFloat tableHeight = MIN(previewHeight, remainingHeight);
CGRect tableFrame = self.tableViewOutlet.frame;
self.tableViewOutlet.frame = CGRectMake(tableFrame.origin.x, tableFrame.origin.y + heightOffset, LIST_WIDTH, tableHeight);
// Selected items
if ([helper getSelectedObject] != nil){
int index = [self.tableData indexOfObject:[helper getSelectedObject]];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:index inSection:0];
[self.tableViewOutlet scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionTop animated:YES];
}
}
}
- (CGSize)contentSizeForViewInPopover {
if (self.navigationController) {
return CGSizeMake(LIST_WIDTH, LIST_MAX_HEIGHT);
} else {
CGFloat totalHeight = [self getHeightWithoutTable] + self.tableViewOutlet.frame.size.height + LIST_STD_SPACE;
return CGSizeMake(LIST_WIDTH, totalHeight);
}
}
(gist if you need some coloring to help you)
An image of the nib :
Just a shot in the dark, since you have not provided any code. If you are adding things to the UITableCellView, just remember that a lot of components have their UserInteractionEnabled set to NO, which will disable the ability to interact with it. Make sure that any items you add to the cell that potentially take up the space where you are tapping (presumably the center of the cell?) have their UserInteractionEnabled set to YES.
The reason why the edges might still work is that the UITableCellView consists of 3 main parts, so you are probably only changing the center part.
Post some code then we can have a better look.
Found the answer myself : the fact I was using a self-filled UIScrollView next to my UITableView seemed to be the problem. As soon as I replaced the UIScrollView by a proper UITableView, the problem disappeared.