How can I reload a TableView using delegation from within my CustomTableViewCell class?
Currently I'm doing it by calling this:
NSNotificationCenter.defaultCenter().postNotificationName(UIContentSizeCategoryDidChangeNotification, object: nil)
But I would like to do it through delegation so I can have more control over the animation and reload only that specific TableViewCell instead of the whole thing.
Any help is greatly appreciated :)
As #Paulw11 suggests in his comment, you can implement a delegate pattern to call back from your custom UITableViewCell to the controller. Be careful not to create any circular references (use weak properties!)
You could also count on the fact that the UITableViewCell is child of the UITableView. That is, if you need to get to the UITableView (vs your controller) you can walk up the superview chain until you find it.
Related
I have a custom UITableViewCell that dequeueReusableCells. I have an int called selectedRow which gets the selected rows number in the method of didSelectRowAtIndexPath. I then pass selectedRow to an int called rowNumber which is in the class of my customCell.
In customCell.m, I have the method prepareForReuse. In that I made an NSLog of rowNumber.
What I want to do is: if a row is selected and that row went off screen, then perform some code. I would probably have to use prepareForReuse, but I don't know what to do in it.
I know it's a bit complicated, but if you have any questions, then I'd be happy to answer
Actually, you don't need to call prepareForReuse directly as it would be called automatically:
this method is invoked just before the object is returned from the
UITableView method dequeueReusableCellWithIdentifier:.
and as you don't know what to do in it, note:
For performance reasons, you should only reset attributes of the cell
that are not related to content, for example, alpha, editing, and
selection state
UITableViewCell Class Reference
You can use - (void)tableView:tableView didEndDisplayingCell:cell forRowAtIndexPath:indexPath; in UITableViewDelegate to know which cell is scrolled off screen.
However, this method is iOS6+ only.
You're over complicating things. You don't have to do prepareForReuse the in the custom cell.
Take a look at this.
http://www.icodeblog.com/2009/05/24/custom-uitableviewcell-using-interface-builder/
Its pretty similar for storyboards.
I'm subclassing UITableViewCell so I can design my own cells with gestures, etc.
One of the things I'm trying is to delete the cell/row after swiping.
My gesture recognizers are all setup and working nicely, however I'm unsure on how to tell the UITableView to delete this object. How can I reference the parent tableView, tell it which row to delete from within the UITableViewCell subclass?
Thanks
You could define a delegate protocol in your UITableViewCell subclass, add a method like cell:didSwipeRightToLeftGesture, and have your cell call its delegate when that happens. Then when your controller receives that delegate message, delete the row from the data source and update the table view.
You could also use UITableView's built-in swipe-to-delete as well.
I am making an interface which have UITableView with four custom UITableViewCell's. And every other UITableViewCell have also UITableView. This mean I have TableView inside a TableView.
Let me call first tableView - ParentTableView and nested tableView - ChildTableView. So I implemented method didSelectRowAtIndexPath on both tableView's. But when the app is running, only the method of the ChildTableView is being called. I need to know inside the ParentTableView, which cell is being tapped.
How can I transfer that information further from ChildTableView to ParentTableView.
This may be a silly question, but I can not find any reliable solution so far, so please help me.
Thank You in advance, kind Sir
First, I think nested table views is a bad idea. But I don't know your use case, so it might be an exception.
The table view controller class used inside a cell have its own #protocol definition and set the outer table view as its delegate. In the inner didSelectRowAtIndexPath: it can inform the outer table view about the selected indexPath, its own indexPath and any other information you might want to transmit.
Try using collection views. You can do a layout that works like a regular table view and then in the cells that need to have a table, you can make those separate cells with another collection view inside or a table view inside of it.
As mentioned before, it's not easy doing table views inside of cells, and it can be very tricky to get things to work correctly.
This is an old tutorial I wrote which may help and be of guidance. But since then there's been collection views and auto layout, so keep in mind it's very old.
Well I have gone through web to search an easy implementation of this question but all I heard is coincide with what I thought at beginning which is not easy enough.
I was wondering if anybody could provide a better and easier implementation to solve this issue.
Well looking at the picture below, (Please neglect the crudeness of the picture)
I have a table view with multiple cells.
And based on the data, there will be different element(s) inside each cell.
If I touch inside the scrollview in cell 2 as shown in the picture. The delegate method for the tableView "didSelectRowAtIndexPath" will NOT be called, which is a problem for me.
So my first thinking is either to trigger the [tableView selectRowAtIndexPath] within the Scrollviews delegate method or I attach another tapGesture to these subviews and trigger it from there. But it already doesn't sound like a intuitive implementation and hard to maintain.
Anybody got any idea how could this be solved in an easier way?
Thanks
There are a wide variety of objectives you might be trying to accomplish here, so I won't speculate on the ultimate goal which you haven't told us, but in general:
If you would like two different UIElements to execute the same chunk of code, then you encapsulate that code in a stand-alone method, and call that method from both places.
In your UIScrollView as a subview of a UITableViewCell example, you would call it from within -(void)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath and you would also call it from the gesture recognizer that you attached to your scrollView.
I will speculate that the part you're having trouble with is knowing which scrollView was touched, or which row the scrollView was in. One possible approach would be to send the UIScrollView or the UITableViewCell as a parameter for the standalone method you created. -(void)doSomethingSpecialWith:(UITableViewCell*)cell or -(void)doSomethingSpecialWith:(UIScrollView)view
Post some more code, or feel free to explain your agenda further, but I have a strong feeling that the best way for you will be to subclass UITableViewCell, add the UIScrollView as a property of the custom cell, and wire up the gesture recognizer to call a method of your subclassed UITableViewCell.
i think the better way to solve this problem is :
creat custom method , - (void)tableviewSeletedIndexPath:(NSIndexPath *)indexPath
you can call this method in TableViews delegate -(void)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath , and call this method in your scrolls method.
Make the tag of scrollView is equal to the current cell row:
scrollView.tag = indexPath.row;
Make your ViewController to be the delegate of UIScrollView and in didScroll get the index and call didSelect:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSIndexPath *index = [NSIndexPath indexPathForRow:scrollView.tag inSection:0];
[self tableView:self.tableView didSelectRowAtIndexPath:index];
}
I've been trying to get my UICollectionView to respond differently to single and double taps but all the answers I have found seem to suggest this is not really feasible because the single taps get recognised first. It works on really slow taps, but anything faster always initiates the default gesture recogniser (if anybody has got this to work I would love to know)...
So anyway, I have now resorted to putting buttons in my UICollectionViewCell (which has it's own class and NIB file).
The question is this:
What is considered the best way to use the button in the UIViewController of the collectionView?
I currently have a protocol in the header of my subclass of UICollectionViewCell and have declared my viewController as the delegate and implemented the required protocol functions.
In collectionView:cellForItemAtIndexPath: I set the VC as the delegate of the cell.
It all works but it seems a bit long-winded, and maybe not a great way of doing this.
The other way I was thinking of was instead of using delegates to simply call addTarget:Action: on the property of the UICollectionViewCell in collectionView:cellForItemAtIndexPath:.
This seems simpler but the delegate pattern looks to me like the better fit.
Any and all advice on which would be better, why, and any more appropriate alternatives welcomed!
Thanks.
You're doing the right think using the delegation pattern. The ultimate responsible object for any action of your views is the viewController who's displaying those views. Therefore, using it as the delegate for you cell's protocol is just right.
create a custom subview of UICollectionViewCell and place your button in the initWithFrame method. Declare the button to be public so you can use it later in your uicollectionviewcontroller or uicollectionview if creating programmatically.