Is there any way that I can get a specific cell to change its style or background image while scrolling the table view?
I want to change the image of a cell which is on top of the visible cells. But only its image is going to be changed the others will stay same, until after scrolling the others come to top of the cells which are shown on the screen. Then the top one's image is going to change this time.
You need to implement scrollViewDidScroll: method of UIScrollViewDelegate in your controller then use visibleCells property of UITableView to get the visible cells of the table.
Something like the following code should work
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
UITableView* tableView;
NSArray* visibleCells;
BOOL first;
tableView = (UITableView*)scrollView;
visibleCells = tableView.visibleCells;
first = YES;
for (UITableViewCell* cell in visibleCells) {
if (first) {
//customize the top cell
first = NO;
}else {
//customize the other visible cells
}
}
}
Related
I have UICollectionView with UICollectionViewCell created in storyboard. I customized cell by adding to it UIImage. After user taps cell I want to show image from particular cell increased by size. To implement that I added UIImageView to view, situated it on top and made:
[previewImage setAlpha:0]; and [previewImage setHidden:YES]; in -viewDidLoad. At -didSelectItemAtIndexPath: I want to set value of image in this UIImageView to the appropriate in touched cell. I tried
previewImage.image = [(CustomCell *)[collectionView cellForItemAtIndexPath:indexPath] image].image;
but it don't works. In logs I see that previewImage.image returns null. So how can I retrieve image value from cell in right way?
Solved by setting previewImage.image this way:
UIImage *preImage = [(CustomCell *)[collectionView cellForItemAtIndexPath:indexPath] image].image;
[previewView setImage:preImage];
hey here you just use the bellow delegate method of UICollectionView
#pragma mark - UICollectionViewDelegate
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
// TODO: Select Item
}
For More info see this UICollectionview-example
i hope this help you..
I have a UITableView populated with custom UITableViewCells. Within those custom cells, I have a UITextField and a "See More" UIButton. The purpose of the UIButton is to dynamically expand that particular UITableCell when the user wishes to read more of the text. In the same way, when the user wishes to return to the original size, the user clicks the Button again, and the UITableViewCell will shrink to the original size.
Since the cell isn't being selected, I setup an IBAction within the Custom Cell like such:
//Within CustomCell.m
- (IBAction)showMoreText:(id)sender
{
//instance bool variable to flag whether the cell has been resized
self.hasBeenResized = YES;
//turn off mask to bounds, otherwise cell doesnt seem to resize
[[self.cellView layer] setMasksToBounds:NO];
// Calculate the new sizes and positions for the textView and the button
CGRect newTextViewFrame = self.textView.frame;
newTextViewFrame.size.height = self.textView.contentSize.height;
self.textView.frame = newTextViewFrame;
CGFloat bottomYPos = self.textView.frame.origin.y + self.textView.frame.size.height;
CGRect buttonFrame = self.showMoreButton.frame;
buttonFrame.origin.y = bottomYPos;
self.showMoreButton.frame = buttonFrame;
// Call begin and end updates
[(UITableView*) self.superview beginUpdates];
[(UITableView*) self.superview endUpdates];
// Set mask and put rounded corners on the cell
[[self.cellView layer] setMasksToBounds:YES];
[[self.cellView layer] setCornerRadius:10.0];
}
Following this, I have this in my ViewController class:
// Within ViewController.m
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"heightForRowAtIndexPath");
CustomCell *cell = (CustomCell*)[self tableView:tableView cellForRowAtIndexPath:indexPath];
if([cell hasBeenResized] == NO)
{
return cell.frame.size.height + 20;
}
else
{
return cell.frame.size.height + cell.textView.frame.origin.y + cell.textView.frame.size.height + cell.showMoreButton.frame.size.height + 20;
}
}
What happens now is I can see the custom cell change the size of its textview, however, the table does not update the row height for that particular cell. Checking on the If-else statement there, it appears that hasBeenResized is always false, even though I set it to YES within the IBACtion of the CustomCell.
I have looked at other solutions here, but they all seem to involve didSelectRowAtIndexPath, which I cannot use in this instance (I have another behavior for the cell when it is selected).
Am I doing this completely wrong? Ideally, what I would like to do is to have the "Show More" button animate downwards as the textview is expanded and vice versa when it's collapsed.
Thank you!
Method beginUpdates won't call reloadData for you - you have to do it manually.
For your case it would be best to call:
- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation
And place your showMoreText code in tableView:cellForRowAtIndexPath: method (for selected cell only)
To Update your tableView, you have to reload it.
[tableView reloadData];
Is there a way for a cell, if used in a grouped table view, detect that fact and modify its appearance as ro not overlap the rounded rect borders?
There are two ways to do this. If you are making a custom cell you can just add a boolean property to the cell and set it when you create the cell. Or, you can do this:
UITableView *parentTable = (UITableView *)self.superview;
if (parentTable.style == UITableViewstyleGrouped {
//Do what you need to do for a grouped cell
}
else {
//Do what you need to do for a plain cell
}
In a grouped table view, such a cell will always be the 1st or last of the section. You can easily identify it in cellForRowAtIndexPath:, by looking at the indexPath parameter.
Is there any way to change the image of the reorder control that is displayed when the UITableView is in edit mode? I have a UIImage that I’d like to display instead of the usual grey bars.
Do I have to subclass UITableViewCell to accomplish this?
I guess you're a long way past this by now, but this has come up in a new question.
See my answer here:
Change default icon for moving cells in UITableView
I recently ran across the need to change the image for the reorder control, because I subclassed UITableViewCell to provide my own custom table cell. As part of this effort, I changed the background of the cell to something other than the default color.
Everything works correctly, but when I put the UITableView into editing mode, the reorder control would appear, with a white background - instead of the background color I was using for the cell. This didn't look good, and I wanted the background to match.
During the course of various versions of iOS, the hierarchy of views in a UITableViewCell has changed. I've taken an approach that will traverse the entire set of views until it finds the UITableViewCellReorderControl private class. I believe this will work for iOS 5 and all subsequent iOS versions at the time of this answer. Please note that while the UITableViewCellReorderControl class itself is private, I am not using any private API's to find it.
First, here's the code to scan for the reorder control; I'm assuming that the text "Reorder" will be in the class name - which Apple could change in the future:
-(UIView *) findReorderView:(UIView *) view
{
UIView *reorderView = nil;
for (UIView *subview in view.subviews)
{
if ([[[subview class] description] rangeOfString:#"Reorder"].location != NSNotFound)
{
reorderView = subview;
break;
}
else
{
reorderView = [self findReorderView:subview];
if (reorderView != nil)
{
break;
}
}
}
return reorderView;
}
In your custom UITableViewCell subclass, you will override -(void) setEditing:animated: and find the reorder control here. If you try to find this control when the table is not in editing mode, the reorder control will not be in the view hierarchy for the cell:
-(void) setEditing:(BOOL)editing animated:(BOOL)animated
{
[super setEditing:editing animated:animated];
if (editing)
{
// find the reorder view here
// place the previous method either directly in your
// subclassed UITableViewCell, or in a category
// defined on UIView
UIView *reorderView = [self findReorderView:self];
if (reorderView)
{
// here, I am changing the background color to match my custom cell
// you may not want or need to do this
reorderView.backgroundColor = self.contentView.backgroundColor;
// now scan the reorder control's subviews for the reorder image
for (UIView *sv in reorderView.subviews)
{
if ([sv isKindOfClass:[UIImageView class]])
{
// and replace the image with one that you want
((UIImageView *)sv).image = [UIImage imageNamed:#"yourImage.png"];
// it may be necessary to properly size the image's frame
// for your new image - in my experience, this was necessary
// the upper left position of the UIImageView's frame
// does not seem to matter - the parent reorder control
// will center it properly for you
sv.frame = CGRectMake(0, 0, 48.0, 48.0);
}
}
}
}
}
Your mileage may vary; I hope this works for you.
Here is my Swift solution based on Rick Morgan's answer:
func adjustSize() {
// we're trying to leverage the existing reordering controls, however that means the table must be kept in editing mode,
// which shrinks the content area to less than full width to make room for editing controls
let cellBounds = bounds
let contentFrame = contentView.convert(contentView.bounds, to: self)
let leftPadding = contentFrame.minX - cellBounds.minX
let rightPadding = cellBounds.maxX - contentFrame.maxX
// adjust actual content so that it still covers the full length of the cell
contentLeadingEdge.constant = -leftPadding
// this should pull our custom reorder button in line with the system button
contentTrailingEdge.constant = -rightPadding
// make sure we can still see and interact with the content that overhangs
contentView.clipsToBounds = false
// recursive search of the view tree for a reorder control
func findReorderControl(_ view: UIView) -> UIView? {
// this is depending on a private API, retest on every new iPad OS version
if String(describing: type(of: view)).contains("Reorder") {
return view
}
for subview in view.subviews {
if let v = findReorderControl(subview) {
return v
}
}
return nil
}
// hunt down the system reorder button and make it invisible but still operable
findReorderControl(self)?.alpha = 0.05 // don't go too close to alpha 0, or it will be considered hidden
}
This worked pretty well. contentLeadingEdge and contentTrailingEdge are layout constraints I set up in Interface Builder between the contentView and the actual content. My code calls this adjustSize method from the tableView(_:, willDisplay:, forRowAt:) delegate method.
Ultimately, however, I went with Clifton's suggestion of just covering the reorder control. I added a UIImageView directly to the cell (not contentView) in awakeFromNib, positioned it, and when adjustSize is called I simply bring the image view to the front, and it covers the reorder control without having to depend on any private APIs.
I put a little work into this recently, but came up short. I tried setting my own editingAccesoryView but couldn't get the reorder control to change. Odd.
My guess is that it has something to do with the following comment in the UITableviewCell docs re: showsReorderControl:
If the value is YES , the reordering
control temporarily replaces any
accessory view.
In other words, the editingAccessoryView is being replaced by the reordering control view, which might be why we cannot override the reordering control. Hoping someone can find a workaround.
You set the cell's editingAccessoryView property to an image view containing the image you want.
As an aside, I would caution you to be careful when doing this. When you substitute a custom graphic for a system standard such as the reorder graphic, you run a serious risk of confusing the user. The standard UI grammar has told them to expect the standard graphic when reordering and they may not understand the significance of your custom graphic.
Maybe we're all overthinking this. :)
Just put a custom UIImageView over the top of the default move accessory so it covers it up. Done.
I have a custom UITableViewCell with a UIScrollView in it that is wired to the cell controller. When I assign text to the scrollview, some cells get the correct text, some are blank, some redisplay old text and others have the scrollview clipped around the 2nd or 3rd line of text. It seems random on what will happen. I followed the suggestion here of using a timer to fix blank cells, http://www.bdunagan.com/2008/12/08/uitextview-in-a-uitableview-on-the-iphone/, but that didn't help. I placed the timer code in the cellForRowAtIndexPath method.
I've also tried calling
[cell.textview setNeedsDisplay];
after text is assigned to the textview but it doesn't have any affect.
When I use a textfield or label, everything looks fine. However, I need something that can scroll text. Any suggestions on a fix or better way?
Update: Found this on the dev forums (specifically mentions your problem):
https://devforums.apple.com/message/38944#38944
I would follow the link it has some more detailed info.
// view controller
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSArray* visibleCells = [self.tableView visibleCells];
for (UITableViewCell* cell in visibleCells)
{
if ([cell.reuseIdentifier isEqualToString:kTextViewCellID])
{
[(MTextViewCell*)cell refresh];
}
}
}
// MTextViewCell
- (void)refresh
{
// mucking with the contentOffset causes the textView to redraw itself
CGPoint contentOffset = mTextView.contentOffset;
CGPoint contentOffset1 = { contentOffset.x, contentOffset.y + 1.0f };
mTextView.contentOffset = contentOffset1;
mTextView.contentOffset = contentOffset;
}
Try calling:
[tableView reloadData];
After you update all the textViews.