Is it possible to add a static background to a collectionview because at the moment the background scrolls with the cells and the image looks quite bad.
my code at the moment
collectionView.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"bg.png"]];
There are 2 ways to do what you're asking.
add the background to the UICollectionView as a subview like you're doing now and implement the scrollViewDidScroll: delegate method. Inside that method, set the frame of the background view based on the contentOffset of the collection view which will make it appear to be static on the screen. You will just need to set the frame's Y origin to be the contentOffset.y and it should work. (If there is a non-zero contentInset you may need to do a bit of additional math to get it right.)
add the background to the superview of your collection view, underneath the collection view. This is an easier and probably more efficient solution since you don't need to mess with the contentOffset at all since the background will not be in the scroll view itself.
if I understand your requirement correctly, here's how you can do it:
1) Add your static image as a subview to the parentView.
2) Set the backgroundColor of collectionView to [UIColor clearColor]
3) Add collection view as a subview to the parentView.
Related
I'm trying to figure out what my options are for having the top of a UITableView be able to stay at rest about 1/3 down the screen but still be able to scroll over the top of an image above it.
I was thinking UITableView on a UIScrollView but I haven't seen this exact thing while googling around for it.
Basically I'm looking to have a header and then the table view will scroll over the top of the header without the header moving. If I set the table view below a simple uiview or imageview, it will always be below it.
Any suggestions?
Add your header as a separate view below your table view. Your table view should completely overlap the underlying view, as if it would obscure it. Then set the table view's tableHeaderView to a transparent UIView, through which you will be able to see your underlying header view. Your table view's background colour should also be clear.
CGRect headerFrame = self.underlyingHeaderView.bounds;
UIView *transparentView = [UIView alloc] initWithFrame:headerFrame];
transparentView.backgroundColor = [UIColor clearColor];
self.tableView.tableHeaderView = transparentView;
What I have in the view controller view are :
An image of fixed height
Few labels
Table view with n rows.
Once rendered I want everything here to be inside the scroll the view so the user can scroll the entire screen as needed. Note that the scrollView needs to expand to the entire size of the tableView to show its full contents. I have tried different ways of doing this but unable to do it. I would appreciate any pointers or code segment to get this done.
There are essentially two ways to do so.
tableHeaderView
The first way involves the tableHeaderView property of the UITableView instance you have. You can simply add the UITableView with the constraints/frame/autoresizingMask that allows you to put it full-screen. Done that, you simply do (i.e. in your viewDidLoad):
UIView *headerView = [UIView new];
// Here I am supposing that you have a 200pt high view and a `self.tableView` UITableView
headerView.frame = CGRectMake(0, 0, self.tableView.frame.size.width, 200.0);
UIImageView *fixedImageView = [UIImageView new];
// configure your imageView..
[headerView addSubview:fixedImageView];
// configure labels as you want and add them to headerView as subviews
// Now set `UITableView` headerView
self.tableView.tableHeaderView = headerView;
If you want to use AutoLayout for your tableHeaderView, I suggest you to take a look at this question
Dynamic scrollView
Another way to do this is to to create an UIScrollView, put everything inside, and let it scroll. The downside of this method is that if you are using floating section headers for your UITableView, they will not float due to the fact that the tableView is going to stay fixed, while the parent scrollView is going to scroll.
On the other side, this approach is more AutoLayout friendly due to the fact you can use constraints easily.
To do so, you start adding an UIScrollView to your view, and placing all your other views inside it.
Be sure to add a Vertical Spacing constraint between the first view inside your scrollView (I suppose the UIImageView) and the scrollView top, and between the last view (I suppose the UITableView) and the scrollView bottom, to avoid an ambiguous content size.
You should have something like that (I omitted the labels for the sake of brevity):
Note that every view is inside a parent UIScrollView
After that, add an Height constraint to the tableView, and add an IBOutlet to your view controller subclass, i.e. like this:
#property (weak, nonatomic) IBOutlet NSLayoutConstraint *tableViewHeightConstraint;
Now you only need to configure this constraint to reflect the tableView natural height, given by its rows, etc. To do so, you simply calculate the height in this way:
// Resize TableView
CGFloat height = self.tableView.contentSize.height;
self.tableViewHeightConstraint.constant = height;
Now the tableView will resize, and due to its constraints it will adapt the parent scrollView contentSize.
Just be sure to refresh this height constraint anytime you reload the UITableView dataSource.
I want to show links between two cells of uiTableView.
For Ex:
To show links between cells 1 and 5, it could be shown like:
Does any one has any idea how this can be achieved. Also when table scrolls, these links should be scrolled with it.
This looks like you want to build hierarchical view. Your implementation might be rejected by Apple due to not taking HIG into account.
Also what will be in case when lower part is not seen to user? Arrow with no end and need to scroll down for the user?
You might want to do a tree like structure (anything hierarchical) instead of ugly (sorry for that) arrows.
If you want arrow between two cell then make a separate UIView class for the Tablecell, in that UIView add one UILabel for text and one UIImageView for arrow, adjust there position as per your requirement.
Now pass this UIView to cell.
Hope this will help you.
UITableViewCell is just a subclass of UIView and UITableView is a subclass of UIScrollView. The only fanciness that UITableView provides is creating/reusing the cells and laying them out in the scroll view. (That's a gross over-simplification but for this It'll do the trick.)
So if I have a UIView subclass that draws an arrow, then it's just a matter of getting the frame for the cells I want to point to. CGRect frame1 = [[self.tableView cellForRowAtIndexPath:indexPath] frame];
Some pseudocode...
topCellFrame = get top cell frame;
bottomCellFrame = get bottom cell frame;
arrow = new arrow view;
arrow set frame = frame with origin of top cell frame origin, and height of distance from topCellFrame to bottomCellFrame;
tableView add subview = arrow;
There are edge cases to think about, If the top cell or bottom cell are offscreen the cellForRowAtIndexPath: will return nil and frame will be CGRectZero.
But I'll leave that as an exercise for you.
Edit: (I haven't done this exact thing, but I have done some similar things with the frames of cells)
I have a UIScrollView which contains a UIView and a UITableView. My goal is to adjust the height of the UIScrollView to allow me to scroll the contents of the UIScrollView to a specific point.
Here is my view: It has a UIView up top and a UITableView down below.
When I scroll, I want the UIView to stop at a specific point like so:
The tableView would be able to continue scrolling, but the UIView would be locked in place until the user scrolled up and brought the UIView back to its original state.
A prime example of what I am trying to do is the AppStore.app on iOS 6. When you view the details of the app, the filter bar for Details, Reviews and Related moves to the top of the screen and stops. I hope this all made sense.
Thanks
I ended up going with a simpler approach. can't believe I didn't see this before. I created two views, one for the UITableView's tableHeaderView and one for the viewForHeaderInSection. The view I wanted to remain visible at all times is placed in the viewForHeaderInSection method and the other view is placed in the tableHeaderView property. This is a much simpler approach, I think than using a scrollview. The only issue I have run into with this approach is all my UIView animations in these two views no longer animate.
Here is my code.
[self.tableView setTableHeaderView:self.headerView];
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
return self.tableViewHeader;
}
add yourself as a UIScrollViewDelegate to the UITableView and implement the - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView so that if your views are in their starter positions they do this:
- your UITableView animates its size to the second state:
[UIView animateWithDuration:.1f animations:^{
CGRect theFrame = myView.frame;
theFrame.size.height += floatOfIncreasedHeight;
myView.frame = theFrame;
}];
- your UIView animates its vertical movement
[UIView animateWithDuration:3 delay:0 options:UIViewAnimationOptionCurveLinear animations:^(void){
view.center = CGPointMake(view.center.x , view.center.y + floatOfVerticalMovement);
}completion:^(BOOL Finished){
view.center = CGPointMake(view.center.x , view.center.y - floatOfVerticalMovement);]
Finally always in the delegate implement – scrollViewDidScrollToTop: so that you know can animate back to the initial state (using the same techniques reversed).
UPDATE:
since your views are inside a scroll view, there is a simpler way if you are ok with the table view being partly out of bounds in your starter position (i.e. instead of changing size it just scrolls into view):
make the scroll view frame size as big as your final tableview + your initial (entire) view and place it at 0,0 (so its final part will be hidden outside of the screen)
scrollview.frame = CGRectMake(0,0,tableview.frame.size.width,tableview.frame.size.height + view.frame.size.height);
you make the container scrollview contents as big as the entire table view + the entire view + the amount of the view that you want out of the way when scrolling the table view.
scrollview.contentSize = CGSizeMake(scrollview.frame.size.width, tableview.frame.size.height + view.frame.size.height + floatOfViewHeightIWantOutOfTheWay);
you place the view one after the other in the scrollview leaving all the additional empty space after the table view
view.frame = CGRectMake(0,0,view.frame.size.width, view.frame.size.height);
tableview.frame = CGRectMake(0,view.frame.size.height, tableview.frame.size.width, tableview.frame.size.height);
now it should just work because since iOS 3 nested scrolling is supported
You can easily achieve this by setting the content size of the scrollView correctly and keep the height of the UITableView smaller than your viewcontroller's height, so that it fits the bottom part of the top UIView and the UITableView...
Another scenario is to split the top View in 2 parts.
The part that will scroll away and the part that will be visible.
Then set the part that will scroll away as the entire UITableView header and the part that will remain visible as the header view for the first table section.
So then you can achieve this with a single UITableView, without having to use a UIScrollView
What you're looking for is something like what Game Center happens to do with it's header which can actually be modelled with a table header, a custom section header view, and some very clever calculations that never actually involve messing with the frame and bounds of the table.
First, the easy part: faking a sticky view. That "view that's always present when scrolling the table" implemented as a section header. By making the number of sections in the table 1, and implementing -headerViewForSection:, it's possible to seamlessly make the view scroll with the tableview all for free (API-wise that is):
- (UITableViewHeaderFooterView *)headerViewForSection:(NSInteger)section {
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0,0,320,50)];
label.text = #"Info that was always present when scrolling the UITableView";
label.textAlignment = UITextAlignmentCenter;
label.backgroundColor = [UIColor colorWithRed:0.243 green:0.250 blue:0.253 alpha:1.000];
label.textColor = UIColor.whiteColor;
return label;
}
Finally, the hard part: KVO. When the table scrolls, we have to keep the header up there sticky with regards to the top of the view's frame, which means that you can KVO contentOffset, and use the resultant change in value to approximate the frame that the view should stick to with a little MIN() magic. Assuming your header is 44 pixels tall, the code below calculates the appropriate frame value:
CGPoint offset = [contentOffsetChange CGPointValue];
[self.tableView layoutSubviews];
self.tableView.tableHeaderView.frame = CGRectMake(0,MIN(0,offset.y),CGRectGetWidth(self.scrollView.frame),44);
If the above is infeasible, SMHeadedList actually has a fairly great, and little known, example of how complicated it can be to implement a "double tableview". That implementation has the added benefit of allowing the "header" tableview to scroll with the "main" tableview.
For future visitors, I've implemented a much simpler version, albeit one that accomplishes the goal with Reactive Cocoa, and a little bit of a different outcome. Even so, I believe it may be relevant.
What if you break the UIView into the top and bottom. The bottom will be the info.
Set UITableView.tableHeaderView = topView in viewDidLoad
and the return bottomView as Section Header in delegate method to make it float:
(UITableViewHeaderFooterView *)headerViewForSection:(NSInteger)section
{
return bottomView;
}
Just using the UITableView can solve with your problem. it is not need to use another scroll view.
set your view as the header view of UITableView. Then add your present view to the header view.
complete - (void)scrollViewDidScroll:(UIScrollView *)scrollView; . Tn the function to check the contentoffset of scroll view, and set the present view's frame.
I have the CNN app on my iPhone.
If you open it will show "top stories", and has always a picture on the top of the table.
When we slide our finger down it expands/zooms the image.
When we slide our finger up to show more rows it does not move the image upwards at the same speed has the table rows instead the table rows move faster than the picture going off the screen.
Do you know how to do this effect?
You need UIImageView to UIScrollView contentInset and set top inset more than zero.
UIScrollView *scroll = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
UIImage *topImage = [UIImage imageNamed:#"photo"];
topImage.frame = CGRectMake(0, -topImage.frame.size.height, topImage.frame.size.width, topImage.frame.size.height);
[scroll addSubview:topImage];
self.contentInset = UIEdgeInsetsMake(topImage.frame.size.height, 0, 0, 0);
After that set UIScrollView's contentOffset like this
scroll.contentOffset = CGPointMake(0, topImage.frame.size.height);
So you have the UIScrollView with image inside it. Now you just need to add delegate to UIScrollView and wait for - (void)scrollViewDidScroll:(UIScrollView *)scrollView. Resize image and change contentInset right after this method called.
This advice you also can apply to UITableView similar way, or create category on UIScrollView.
I also advice you to read code of this project https://github.com/samvermette/SVPullToRefresh. It's also about UITableView and adding view to it's top side
It seems like a completely custom effect that you will have to implement yourself. To point you in the right direction, I'd first monitor contentOffset changes in the scrollViewDidScroll: messages sent by your myTableView instance, and when the contentOffset.y < 0, change the scale of your imageView via
[myImageView setValue:[NSNumber numberWithFloat:scaleIncrementAmountFloat] forKeyPath:#"transform.scale"];
My guess is that the top cell (or cells) of the tableview are transparent and there is a UIImageView behind the tableview that is resized/moved based on how the table view is scrolled.
Since the table view inherits from UIScrollView, its delegate (UITableViewDelegate) inherits from the UIScrollViewDelegate protocol which is notified when a the user scrolls the scroll view. Implement the - (void)scrollViewDidScroll:(UIScrollView *)scrollView method to receive these notifications and check the contentOffset property on the scroll view.
You may have to implement you own table view controller to build the desired UI in the interface builder.