I am using collection view for the first time and I'm not sure how to do something..
I have a UICollectionView with 12 cells. I set the collectView to scroll horizontally only and cells are lined up next to each other. I also turned on paging so I could use UIPageControll to indicate scrolling is active.
I want the collection view to only show four cells on the screen at any time. When the view loads, I get four cells, no problem. However when I scroll horizontally, I get 4 and a half cells. never just four.
Is there a way to tell the collection view only to show four cells at a time?
you can statically add number of cell(items)in collection view,if not require dynamic.
here I am using Scroll Direction Horizontal you can do it same way in vertical.
hope this will help
you can do this way also. Just copy this code into your view controller and make some changes.
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
NSIndexPath *indexPath;
for (UICollectionViewCell *cell in [self.collectionView visibleCells]) {
indexPath = [self.collectionView indexPathForCell:cell];
NSLog(#"%#",indexPath);
}
UICollectionViewCell *cell =(UICollectionViewCell *)[self.collectionView cellForItemAtIndexPath:indexPath];
//finally get the rect for the cell
CGRect cellRect = cell.frame;
self.collectionView.contentOffset = CGPointMake(self.collectionView.contentOffset.x, cellRect.origin.y);
}
As Marc said, you could simply control the size of your collection view.
If changing the size is not practical, then you can set content inset on the collection view.
CGFloat cellWidth = … // Cell width
CGFloat collectionViewWidth = … // Collection View Width
CGFloat desiredCollectionViewWidth = cellWidth * 4.0;
CGFloat horizontalInset = collectionViewWidth - desiredCollectionViewWidth;
// To center the collection view
UIEdgeInsets inset = UIEdgeInsetsMake(0, horizontalInset/2, 0, horizontalInset/2);
self.collectionView.contentInset = inset;
// Or, to left justify the collection view
UIEdgeInsets inset = UIEdgeInsetsMake(0, 0, 0, horizontalInset);
self.collectionView.contentInset = inset;
Related
Currently, I've developed project that UIScrollView, UITableView, another 3 more UIView inputs and UIButton at the last. In that page, UIScrollView height will be dynamically increased based on height of UITableView.
For UITableView there is no more scrolling. Its height will be increased as well based on how many rows are added based on JSON data loaded by Async as follow.
productHeight = 44;
productHeight *= _nsOrderItems.count;
productHeight = productHeight + 100;
if (isHeaderTap) {
self.productTableHeight.constant = 50;
} else {
self.productTableHeight.constant = productHeight;
}
//then the tableView must be redrawn
[self.productTable setNeedsDisplay];
My Problem is I want to increase height of UIScrollView based on height of UITableView.
- (void)viewDidLayoutSubviews {
[self.scrollView setContentSize:CGSizeMake(_scrollView.frame.size.width, _btnEdit.frame.origin.y + _btnEdit.frame.size.height)];
}
You can definitely do that,
First make sure your constraint of cells subView must set to top to bottom in order to calculate the height required for the cell.
Make sure your delegated are set as below
-(CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowAtIndexPath:(NSIndexPath *)indexPath {
return 44;
}
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
return UITableViewAutomaticDimension;
}
Set height constraint of your tableView and make outlet of that constraint.
Add below method to your class where you want to resize your tableView dynamically.
- (void)adjustHeightOfTableview
{
CGFloat height = self.tableView.contentSize.height;
//CGFloat maxHeight = self.tableView.superview.frame.size.height - self.tableView.frame.origin.y;
/*
Here you have to take care of two things, if there is only tableView on the screen then you have to see is your tableView going below screen using maxHeight and your screen height,
Or you can add your tableView inside scrollView so that your tableView can increase its height as much it requires based on the number of cell (with different height based on content) it has to display.
*/
// now set the height constraint accordingly
self.constraintHeightTableView.constant = height;
//If you want to increase tableView height with animation you can do that as below.
[UIView animateWithDuration:0.5 animations:^{
[self.view layoutIfNeeded];
}];
}
Call this method when you are ready with the dataSource for the table, and call the method as
dispatch_async(dispatch_get_main_queue(), ^{
[self.tableView reloadData];
//In my case i had to call this method after some delay, because (i think) it will allow tableView to reload completely and then calculate the height required for itself. (This might be a workaround, but it worked for me)
[self performSelector:#selector(adjustHeightOfTableview) withObject:nil afterDelay:0.3];
});
// Get the supposed to be height of tableview
CGFloat height = self.tableViewMenu.contentSize.height;
// get the height constraint of tableview and give it you respected height
self.constraintHeightTableView.constant = height;
// set the scroll
NOTE:- don't forget to disenable the scrolling of table from storyboard or programmatically
self.scrollView.contentSize = CGSizeMake(self.scrollView.contentSize.width, self.viewUserLogin.frame.size.height + height);
[self.scrollView layoutIfNeeded];
I would like to fire an event when the subview of a UITableviewCell reaches a certain point on the screen, say for example when its origin.y reaches 44 points. It would also be nice to know if it was being scrolled up or down when it reached that point. I was playing with KVO on the frame of the subview but this seems fixed to the cell so no changes with that. Is this task possible?
Vertical position of UITableViewCell is defined by its frame property, which represents position and size of that cell within its superview, UITableView. Typically, the frame property of the cell is changing only once for every time that UITableView requests a cell from its delegate for specific index path. That's it, UITableView gets a cell, places it in itself and that cell just lays there unchanged until rectangle stored in bounds property of UITableView ceases to include rectangle stored in the frame property of that cell. In that case UITableView marks that cell as hidden and places it into the pool of reusable cells.
Since the process of scrolling in essence is not a repositioning of subviews – it is merely a curious illusion of shifting a bounds viewport of UITableView – constant observing of UITableViewCell's properties are pointless.
Moreover, the frame property of subview of UITableViewCell also represents a position and size of that subview within its container, UITableViewCell. It is also will not change on scroll.
You need to observe changes in UITableView bounds property, which is also represented by contentOffset by the way. UITableView happens to be a subclass of UIScrollView, so you can use its delegate methods, such as -scrollViewDidScroll:, like in this simple example:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
UITableView *tableView = (UITableView *)scrollView;
// current position
CGFloat currentY = tableView.bounds.origin.y;
// current inset
CGFloat currentInset = tableView.contentInset.top;
// trigger line position
CGFloat triggerY = currentInset + currentY + kYourTriggerPosition;
// nice visual mark
UIView *line = [tableView viewWithTag:88];
if (!line) {
line = [[UIView alloc] initWithFrame:CGRectZero];
line.tag = 88;
line.backgroundColor = [UIColor redColor];
[tableView addSubview:line];
}
line.frame = CGRectMake(0, triggerY, tableView.bounds.size.width, 1);
// determine scroll direction
BOOL scrollingUp = currentY > self.previousY;
// all visible cells
NSArray *visibleCells = tableView.visibleCells;
[visibleCells enumerateObjectsUsingBlock:^(UITableViewCell *cell, NSUInteger idx, BOOL *stop) {
// subview
UIView *subview = [cell viewWithTag:kYourSubviewTag];
// subview frame rect in UITableView bounds
CGRect subviewRect = [subview convertRect:subview.frame toView:tableView];
// trigger line within subview?
BOOL triggered = (CGRectGetMinY(subviewRect) <= triggerY) && (CGRectGetMaxY(subviewRect) >= triggerY);
if (triggered) {
NSIndexPath *indexPath = [tableView indexPathForCell:cell];
NSLog(#"moving %#, triggered for cell at [%2d:%2d]", #[#"down", #"up"][scrollingUp], indexPath.section, indexPath.row);
[tableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionNone];
}
}];
// save current position for future use
self.previousY = currentY;
}
Reach that subview of UITableViewCell with cellForRowAtIndexPath or tableView.visibleCells, then call convertRectToView: on that subview.
convertRectToView: allows you to do translations on different coordinate systems. For example, you can detect where that subview appears on screen by translating its frame within its superview into viewController.view
For more: Apple Documentation
Since I can not comment I am writing as an Answer
Changing the answer for the requirement.
Here is how I think it can be done, you need to have your custom UITableViewCell which has a function which can take in co-ordinates (again based on your logic if you just want an intersection where a cell just touches a boundary or if it has to be at a precise position in a frame), so your function would take the co-ordinates and will return a true and a false if it will tell you if the condition is met, and in your cellForTable function you call the function of UITableView cell to check if your condition is met, if it is in your view you create a subview at the exact location. You can also modify the function to return you the exact frame-cordinates so you can use them to create a subview\
Here's a simple approach, which you can use if you have only one section without section header.
Add this to your implementation:
CGFloat lastContentOffSet;
And then add this delegate method of scrollview as tableview is also a scrollview.
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
CGFloat cellHeight = 50;
CGFloat touchingPoint = 44.0f;
NSInteger rowNo = floor(scrollView.contentOffset.y / cellHeight);
NSInteger startPoint = (rowNo * cellHeight);
if (scrollView.contentOffset.y > lastContentOffSet) {
NSLog(#"Row %ld scrolled down", (long)rowNo);
if (scrollView.contentOffset.y > startPoint + touchingPoint) {
// Do something here
NSLog(#"Do something here");
}
}
else {
NSLog(#"Row %ld scrolled up", (long)rowNo);
if (scrollView.contentOffset.y > startPoint + touchingPoint) {
// Do something here
NSLog(#"Do something here");
}
}
lastContentOffSet = scrollView.contentOffset.y;
}
Change value of the cellheight according to your tableview cell and the distance of that subview with the cell.
Let me know if this code helped. :)
I have a tableView with dynamically generated custom cells and one of the custom cell contains a scrollView that can scroll vertically and a page control is attached to it.
The user interface structure of the tableview can be seen in the photo.
I am refreshing the position of the page control in the scrollViewDidScroll method as follows.
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSIndexPath *indexPathPageControl=[NSIndexPath indexPathForRow:0 inSection:0];
UITableViewCell * cell = (UITableViewCell*)[self.sonDakikaTableView cellForRowAtIndexPath:indexPathPageControl];
CGFloat xOffset = scrollView.contentOffset.x;
CGFloat frameWidth = scrollView.frame.size.width;
int page = floor((xOffset - frameWidth / 2) / frameWidth) + 1;
UIPageControl *pageControl = (UIPageControl *)[cell.contentView viewWithTag:14];
pageControl.currentPage = page; // assigning to pagecontroll
}
It is working very fine when the user is scrolling vertical in the scrollView.
However when the user scrolls down on the tableView and the cell with vertical scrollView is not visible anymore, the integer page variable is being updated with 0 and when the user scrolls up and table view cell is visible again, the location of page control is being reset.
I will appreciate if someone can give me an idea about how to prevent this.
Thanks in advance.
i added this code
(void)scrollViewDidScroll:(UIScrollView *)_scrollView
{
if (_scrollView == self.tableView) return;
and in your case
(void)scrollViewDidScroll:(UIScrollView *)_scrollView
{
if (_scrollView == self.sonDakikaTableView) return;
I have a UITableView nested within a UIScrollView and am finding it hard to calculate the height of either.
The content of both is dynamic so I'd like the tableview to expand to fit the content of it, and in turn the scrollview to expand to fit the content of the tableview.
I have this for the scrollview:
CGFloat scrollViewHeight = 0.0f;
for (UIView* view in contentView.subviews)
{
scrollViewHeight += view.frame.size.height;
}
But the resultant height is too long, too much scrolling.
The tableview I'm finding harder to get to dynamically resize, if I leave it without a defined size it is too small. So I added this:
self.tableView.contentSize = CGSizeMake(320.0f, [self.tableView contentSize].height);
And that's too big.
I think the size of the tableview is dictated by the number and height of the rows within it but can't find a clear answer here or on the net.
Any ideas?
Your UITableViewDelegate should implement:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
This will set the correct size for your cell.
I use the following code to set the height of UIScrollView:
for (UIView* view in scrollview_.subviews)
{
if (!view.hidden)
{
CGFloat y = view.frame.origin.y;
CGFloat h = view.frame.size.height;
if (y + h > scrollViewHeight)
{
scrollViewHeight = h + y;
}
}
}
[scrollview_ setContentSize:(CGSizeMake(320, scrollViewHeight))];
To get the height of UITableView, maybe you can calculate like rowheight*rowcount
I have been working on this for about 2 days, so i thought i share my learnings with you.
The question is: Is it possible to make the width of a cell in a grouped UITableView smaller?
The answer is: No.
But there are two ways you can get around this problem.
Solution #1: A thinner table
It is possible to change the frame of the tableView, so that the table will be smaller. This will result in UITableView rendering the cell inside with the reduced width.
A solution for this can look like this:
-(void)viewWillAppear:(BOOL)animated
{
CGFloat tableBorderLeft = 20;
CGFloat tableBorderRight = 20;
CGRect tableRect = self.view.frame;
tableRect.origin.x += tableBorderLeft; // make the table begin a few pixels right from its origin
tableRect.size.width -= tableBorderLeft + tableBorderRight; // reduce the width of the table
tableView.frame = tableRect;
}
Solution #2: Having cells rendered by images
This solution is described here: http://cocoawithlove.com/2009/04/easy-custom-uitableview-drawing.html
I hope this information is helpful to you. It took me about 2 days to try a lot of possibilities. This is what was left.
A better and cleaner way to achieve this is subclassing UITableViewCell and overriding its -setFrame: method like this:
- (void)setFrame:(CGRect)frame {
frame.origin.x += inset;
frame.size.width -= 2 * inset;
[super setFrame:frame];
}
Why is it better? Because the other two are worse.
Adjust table view width in -viewWillAppear:
First of all, this is unreliable, the superview or parent view controller may adjust table view frame further after -viewWillAppear: is called. Of course, you can subclass and override -setFrame: for your UITableView just like what I do here for UITableViewCells. However, subclassing UITableViewCells is a much common, light, and Apple way.
Secondly, if your UITableView have backgroundView, you don't want its backgroundView be narrowed down together. Keeping backgroundView width while narrow down UITableView width is not trivial work, not to mention that expanding subviews beyond its superview is not a very elegant thing to do in the first place.
Custom cell rendering to fake a narrower width
To do this, you have to prepare special background images with horizontal margins, and you have to layout subviews of cells yourself to accommodate the margins.
In comparison, if you simply adjust the width of the whole cell, autoresizing will do all the works for you.
To do this in Swift, which does not provide methods to set variables, you'll have to override the setter for frame. Originally posted (at least where I found it) here
override var frame: CGRect {
get {
return super.frame
}
set (newFrame) {
let inset: CGFloat = 15
var frame = newFrame
frame.origin.x += inset
frame.size.width -= 2 * inset
super.frame = frame
}
}
If nothing works you can try this
Make the background colour of the cell as clear color and then put an image of the cell with required size. If you want to display some text on that cell put a label above the image. Don't forget to set the background color of the label also to clear color.
I found the accepted solution didn't work upon rotation. To achieve UITableViewCells with fixed widths & flexible margins I just adapted the above solution to the following:
- (void)setFrame:(CGRect)frame {
if (self.superview) {
float cellWidth = 500.0;
frame.origin.x = (self.superview.frame.size.width - cellWidth) / 2;
frame.size.width = cellWidth;
}
[super setFrame:frame];
}
The method gets called whenever the device rotates, so the cells will always be centered.
There is a method that is called when the screen is rotated : viewWillTransitionToSize
This is where you should resize the frame. See example. Change the frame coords as you need to.
- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
{
[coordinator animateAlongsideTransition:nil completion:^(id<UIViewControllerTransitionCoordinatorContext> context)
{
int x = 0;
int y = 0;
self.tableView.frame = CGRectMake(x, y, 320, self.tableView.frame.size.height);
}];
}
i do it in
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell;
CGFloat tableBorderLeft = self.view.frame.origin.x + 10;
CGFloat tableBorderRight = self.view.frame.size.width - 20;
CGRect tableRect = self.view.frame;
tableRect.origin.x = tableBorderLeft;
tableRect.size.width = tableBorderRight;
tableView.frame = tableRect;
}
And this worked for me
In .h file add the delegate 'UITableViewDataSource'
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return size;
}