When using selectRowAtIndexPath:animated:scrollPosition:, I am passing in UITableViewScrollPositionNone. Despite the name, I am expecting the tableview to scroll when necessary so that the row is visible (and not scroll if it is already visible).
UITableViewScrollPositionNone -
The table view scrolls the row of interest to be fully visible with a minimum of movement. If the row is already fully visible, no scrolling occurs. For example, if the row is above the visible area, the behavior is identical to that specified by UITableViewScrollPositionTop. This is the default.
However, I am finding that the table view does not scroll at all. If I use UITableViewScrollPositionTop or UITableViewScrollPositionBottom, the table view scrolls as expected.
Can it be possible that the documentation for this is incorrect? Or am I missing something?
The documentation for UITableView's selectRowAtIndexPath:animated:scrollPosition: has a section that describes what you are experiencing.
Special Considerations Passing UITableViewScrollPositionNone will
result in no scrolling, rather than the minimum scrolling described
for that constant. To scroll to the newly selected row with minimum
scrolling, select the row using this method with
UITableViewScrollPositionNone, then call
scrollToRowAtIndexPath:atScrollPosition:animated: with
UITableViewScrollPositionNone.
Hope that helps!
You need to make sure that the table view's content view has the space to scroll. I once need to scroll the table view because user tap on a text field and the keyboard came up, I need the extend the table view's content to the height of the keyboard's height so that the table view can scroll. Like this:
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, keyboardFrame.size.height, 0.0);
self.tableView.contentInset = contentInsets;
self.tableView.scrollIndicatorInsets = contentInsets;
[self.tableView scrollToRowAtIndexPath:self.currentEditingCellIndexPath atScrollPosition:UITableViewScrollPositionNone animated:YES];
Related
I'm having a problem with auto layout in a collection view cell in iOS 9.
During the collection view's :cellForItemAtIndexPath: I change a constraint:
[[self rootStack] setDistribution:UIStackViewDistributionFillEqually];
or
[[self rootStack] setDistribution:UIStackViewDistributionFillProportionally];
During the cell's preferredLayoutAttributesFittingAttributes: I try to force an additional round of layout:
- (UICollectionViewLayoutAttributes*) preferredLayoutAttributesFittingAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes
{
[self setNeedsLayout];
[self layoutIfNeeded];
return layoutAttributes;
}
Still, when cells are displayed, some show the effect of the constraint change and some do not. If I scroll a cell that does not display the change offscreen and then scroll back to it, it then displays the change. Moving the constraint changes to the cell's updateConstraints resulted in none of the cells showing the change on first display.
I can fix this for the first cells that are displayed by calling reloadData on the collection view during the collection view controller's viewWillAppear:. But once I start scrolling some of the cells that come into view are not formatted correctly (unless I scroll past them and then scroll back to them).
Is there a way I can make sure that all cells are formatted correctly the first time they are displayed?
I have already built out 2 collection views, 1 horizontally scrolling (at the top) & 1 vertically scrolling (at the middle - bottom) that are used to view 2 different sets of content in my Objective-C iOS application similar to this Instagram screenshot:
I am trying to add functionality to make it so that the horizontally scrolling Collection View disappears when the user scrolls up on the vertically scrolling one. What is the best way to accomplish this task? I have looked up tutorials on adding a collection view in another collection view's cell but I cant find anything on just adding a collection view to the 1st cell of another collection view. What would be the best way to accomplish this functionality?
I think you should you use UITableView with UICollectionView. On the screeshot, I think horizontal collectionview is embedded in first cell of the tableview. And when use starts to scroll tableview, first row is gone as you want.
Edit
Create uitableview with 2 prototype cells. Create horizontall collectionview and embed it in first cell of tableview, this is first prototype cell. Then create second prototype cell for images. And when user will start scroll the tableview first cell will gone, as you want.
If you don't want to go with the other suggested method of embedding the horizontal collection view into the top cell of the vertical collection view, you could use the vertical collection view's scrolling callbacks (scrollViewDidScroll, since UICollectionView subclasses UIScrollView). When the vertical collection view scrolls, you can apply a transform to the top collection view to move it off the top of the screen based on the contentOffset of the vertical collection view, and then have it reappear once the contentOffset approaches 0.
Keep in mind that with this approach, the vertical collection view's frame will likely be the height of the screen minus the height of the horizontal collection view. Therefore, you will need a bit of extra logic to expand the vertical collection view's frame to take up the whole screen once the horizontal collection view has disappeared from sight. Otherwise, you will have an awkward blank bar at the top of the screen where the horizontal collection view initially was while you scroll.
You have two scroll view lets call it "cvHorizontal" and "cvVertical".
You can manage scrollViewDidScroll method to hide cvHorizontal when scrolled up and show cvHorizontal when scrolled down.
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
if (lastContentOffset > scrollView.contentOffset.y){
[self showCategory:YES];
lastContentOffset = scrollView.contentOffset.y;
} else if (lastContentOffset < scrollView.contentOffset.y) {
[self showCategory:NO];
lastContentOffset = scrollView.contentOffset.y;
}
}
-(void)showCategory:(BOOL)flag{
if(flag){
[UIView animateWithDuration:0.6 animations:^{
if(cvHorizontal.hidden ){
cvHorizontal.hidden=NO;
cvHorizontalHeight.constant=65.0f;//manage the cvHorizontal height and all the other constraints calculation if any
}
}];
}else {
[UIView animateWithDuration:0.6 animations:^{
cvHorizontal.hidden=YES;
cvHorizontalHeight.constant=0;
}];
}
}
I have a container view created in a xib, I have added various textfields to that container view, In a case when the user reaches that view controller I want the container view to automatically scroll to a particular textfield and focus on it.
Note that I am not using scroll view as of and I am trying to know is there a way to do it without using UIScrollView
There is no ability to make a UIView scroll in of itself. I would recommend using either a scroll view or a table view. If you decide to use a table view, you would have your textfields in individual cells, then you could do something like this to scroll:
//Scroll to 4th text field
NSIndexPath *indexToScrollTo = [NSIndexPath indexPathForRow:3 inSection:0];
[self.tableView scrollToRowAtIndexPath:indexToScrollTo
atScrollPosition:UITableViewScrollPositionTop
animated:YES];
In a scroll view, you would set the content offset to scroll to a particular y position. Here's an examle:
//Scroll down by 50
self.scrollView.contentOffset = CGPointMake(0,50);
yes,you can do it by using TableViewController. it automatically focus on the text fields and automatically scroll up when keyboard appears.
I currently have a view controller that is comprised of a Navigation bar, followed by a UIView that has two UIButtons added as subViews. There is then a UITableView underneath that begins at the bottom of the container UIView.
At the moment, when the user scrolls the UITableView it goes behind the UIView and UIButtons. What I actually want to happen is for the UIView and UIButtons to move up with the table view but only by the value of their height which in this case is 58 pixels. The flow would be like this...
1) Table scrolls and the UIView moves with it for the first 58 pixels.
2) The user continues to scroll the table but the UIView "pins" itself just out of view under the navigation bar.
3) When the user scrolls the table back down the UIView is then picked up and dragged back into view. I believe the new Facebook app does something similar in the timeline.
I don't want to set the UIView as the TableHeaderView of the table as I also have a pull-to-refresh which then sits above the buttons and looks terrible. I've tried playing around with the contentOffset properties of the underlying scrollview of the table but have hit a brick wall.
Any advice on where to start would be appreciated.
Thanks
EDIT: I am gotten a little further and using this code to move the frame of the UIView.
-(void) scrollViewDidScroll:(UIScrollView *)scrollView
{
NSLog (#"Content Offset: %f", self.tableView.contentOffset.y);
NSLog (#"Button Frame: %f", self.btnBackground.frame.origin.y);
if (self.tableView.contentOffset.y > 0)
{
CGRect newFrame = self.btnBackground.frame;
newFrame.origin.x = 0;
newFrame.origin.y = -self.tableView.contentOffset.y;
[self.btnBackground setFrame: newFrame];
}
}
The problem now is that the scrollViewDidScroll delegate method doesn't get fired quickly enough if the table view is scrolled fast. The result is that the UIView doesn't quite make all way back to its original position when scroll quickly.
The scroll content offset is a good idea. Also if you tableview has only one section one approach is to do a custom header view representing the top level widgets. If there is more than one sections create an additional empty section which would return your custom header.
You can refer to this stack overflow post.
Customize UITableview Header Section
Well Asked Question (y)
well , for me i would first : use a main UIScrollView that contains both your topView and the tableView under it and that has the same width as your top UIView and UITableView and set its height to be height(tableView) + height(topView).
Second : since UITableView is a subClass of UISCrollView you can use scrollViewDidScroll delegate to know if the tableview is scrolled up or down.
in this cas you will have Two cases :
1) tableview is scrolled up = > you set the content offset of the main scrollView to be
[scrollView setContentOffset:CGPointMake(0, 58) animated:YES];
2) when the table view is scrolled down you can reset the content offset again
[scrollView setContentOffset:CGPointMake(0, 0) animated:YES];
I have a UITableView with a UIToolbar-like view at the bottom of the screen. I'd like to dynamically animate the toolbar to slide up and down to appear and disappear on the screen when the user takes certain actions on the table data. The problem I'm encountering is that when I animate the toolbar upward, it covers the last few letters of the index.
I'd like to shrink the index size as an animation, along with the toolbar animation. The standard UITableView index functionality doesn't provide us access to this view, just what the view displays, via sectionIndexTitlesForTableView. What's the best way to go about modifying it in such a way?
One way is to animate the entire table view height. This will also prevent your toolbar from covering basically the last cell in case they wanted to do something with it while the toolbar is up.
If you have a UITableViewController then you might have to move your code into a normal UIViewController.
Another way is to enumerate through the subviews of your table view and find the section title view that way, though I'm not sure if that would work very well.
Remember that UITableView is just another scrollview. Just adjust the contentInset and scrollIndicatorInsets according to your toolbar's height:
UIEdgeInsets contentInset = self.tableView.contentInset;
contentInset.bottom = self.myToolbar.frame.size.height;
self.tableView.contentInset = contentInset;
UIEdgeInsets scrollInset = self.tableView.scrollIndicatorInsets;
scrollInset.bottom = self.myToolbar.frame.size.height;
self.tableView.scrollIndicatorInsets = scrollInset;