Basically I am storing an index of an array in a NSInteger. I now need it as an NSIndexpath, I'm struggling to see and find a way to convert my NSInteger to NSIndexpath so I can reuse it.
For an int index:
NSIndexPath *path = [NSIndexPath indexPathWithIndex:index];
Creates Index of the item in node 0 to point to as per the reference.
To use the indexPath in a UITableView, the more appropriate method is
NSIndexPath *path = [NSIndexPath indexPathForRow:row inSection:section];
If you need a NSIndexPath for a UITableView, you can use indexPathForRow:inSection: (reference). Index paths passed to table view must contain exactly two indices specifying the section and row. An index path created with indexPathWithIndex: only contains one index and won't work with a table view.
Use below methods of NSIndexPath class.
+ (id)indexPathWithIndex:(NSUInteger)index;
+ (id)indexPathWithIndexes:(NSUInteger *)indexes length:(NSUInteger)length;
- (id)initWithIndex:(NSUInteger)index
Use as below and also Don't forget to release myIndexPath object after using.
NSIndexPath *myIndexPath = [[NSIndexPath alloc] initWithIndex:[myIntObj intValue]];
Swift 3:
let indexPath = IndexPath(row: 0, section: 0)
Related
I am getting nil UITableviewcell,check my below code.
int random = arc4random() % arr.count;
NSInteger index = [[arr objectAtIndex:random-1] integerValue];
NSIndexPath *path = [NSIndexPath indexPathForRow:index inSection:0];
SongListCell *cell2 = (SongListCell *)[table_view cellForRowAtIndexPath:path];
Getting nill cell.
what is wrong? what i am doing wrong?
Method cellForRowAtIndexPath: returns nil if cell is not visible or index path is out of range
I'm not sure exactly what you're trying to achieve, but I think that maybe the second row of your code shouldn't be there. Is that possible? Shouldn't it be:
int random = arc4random() % arr.count;
NSIndexPath *path = [NSIndexPath indexPathForRow:random-1 inSection:0];
SongListCell *cell2 = (SongListCell *)[table_view cellForRowAtIndexPath:path];
Because otherwise, your depending on the values inside arr and not just on the amount of objects in arr, and these values may contain invalid indices (or maybe even non numeric ones).
If that's not the case, can you please provide an example of values from arr?
You should create the cell yourself if it is nil, alternatively in your viewDidLoad or where appropriate, you can call one of these methods to make the tableview create the cells for you.
[self.tableView registerClass:<#(__unsafe_unretained Class)#> forCellReuseIdentifier:<#(NSString *)#>]
[self.tableView registerNib:<#(UINib *)#> forCellReuseIdentifier:<#(NSString *)#>]
This question already has answers here:
Convert NSInteger to NSIndexpath
(4 answers)
Closed 7 years ago.
I am making a basic quiz application.The choices are in the form of a table view. If the user moves to a previous question, I want to show him his previously selected choice. I have stored the choice in NSUserDefaults. How do I convert this int value to NSIndexpath and use it in my tableview?
See the NSINdexPath UIKit Additions
In your case you can use (Swift):
let indexPath = NSIndexPath(forRow: 0, inSection: 0)
Swift 3.0:
let indexPath = IndexPath(row: 0, section: 0)
Duplicate of This post
I copied the recieved answer here
For an int index:
NSIndexPath *path = [NSIndexPath indexPathWithIndex:index];
Creates Index of the item in node 0 to point to as per the reference.
To use the indexPath in a UITableView, the more appropriate method is
NSIndexPath *path = [NSIndexPath indexPathForRow:yourInt inSection:section];
You can get indexpath using below code
NSIndexPath *index = [NSIndexPath indexPathForRow:YOURINTSTORED inSection:0];
I am trying to follow the following post on reload a cell in a UICollectionView:
UICollectionView update a single cell
I know that I ultimately want something that looks like this:
[self.collectionView reloadItemsAtIndexPaths:??];
But I don't know how to find and pass the indexPath of a particular cell. Can anyone provide any pointers?
I have an NSMutableArray that contains all the cell information (imageViews that are generated in each cell). Ideally, what I'd like to do is pass the index of the NSMutableArray to refresh the corresponding cell on the page. But I'm not sure how the numerical index gets translated into an indexPath.
Thanks in advance for your help!
It depends on your implementation and how you have grouped your cells into sections but let's assume you have one section and each element in your array corresponds to a row in your table.
If you wanted to reload a cell corresponding to an array element at index x all you need to do is write
[_collectionView performBatchUpdates:^{
[_collectionView reloadItemsAtIndexPaths:#[[NSIndexPath x inSection:0]]];
} completion:^(BOOL finished) {}];
Conversely, if you have the cell but want to find its index path you can always call [collectionView indexPathForCell:myCell]
Toy have to pass an array containing the indexPaths that you want to be reloaded.
[self.collectionView reloadItemsAtIndexPaths: indexpathArray];
NSIndexPath has some property names section and row, both represents a cell. If your collection view has single section, you can create a NSIndexPath by setting its section = 0;
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:rowIndex inSection:0];
Here rowIndex is your array index. Btw you have to make an array with you newly created indexpaths, then pass it to reloadItemsAtIndexPaths.
Hope this helps.. :)
Obj-C
NSMutableArray *indexPaths = [[NSMutableArray alloc] init]
[indexPaths addObject:indexPath];
[self.collectionView reloadItemsAtIndexPaths: indexPaths];
Swift 4.0
var indexPaths = [IndexPath]()
indexPaths.append(indexPath)
if let collectionView = collectionView {
collectionView.reloadItemsAtIndexPaths(indexPaths)
}
You can use this way for Swift 5.1:
collectionViewOutletName.reloadItems(at: [IndexPath(row: indexNumber, section: sectionNumber)] )
You can use this way for Swift 5:
CollectionView.reloadItems(at: IndexPath])
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
NSDictionary *dic = #{#"option":[NSNumber numberWithBool:YES]};
[self.array insertObject:dic atIndex:indexPath.row];
[collectionView reloadItemsAtIndexPaths:#[indexPath]];
}
I have a uitableview that hosts a number of cells, in another part of the app the user will make an NSString selection that will match on of the cells in the uitableview, how can I select hat cell programmatically?
I tried using the method
selectRowAtIndexPath:animated
but how can I get the indexpath? is there a better way?
I think you are loading data from an array. Then just search inside that NSArray and take index of the matched object. Now you can create NSIndexPath programatically:
[NSIndexPath indexPathForRow:index inSection:section];
Just use this NSIndexPath to select the row
try this .... first try to get the cell number based on string
NSString * pUserSelectedString = #"abcd";
int index;
if([array containsObject:pUserSelectedString])
{
index = [array indexOfObject:pUserSelectedString];
}
The way you needs to get the indexpath from source array is
int selectionIndex;
if([sourceArray containsObject:userSelectionString])
{
selectionIndex = [sourceArray indexOfObject:userSelectionString];
}
You have to check whether selection object is there or not before get the indexpath from sourceArray.then you have to use this indexpath for selectRowAtIndexpath:animated method
I have a UIcollectionview that shows an array of objects called Items.
At one point in the lifecycle of my app I do need to move the collectionview ( or scroll it ) to a specific Item that I receive Via NSnotification. I do not know the NSIndexPath of that Item but its definitely available in the collectionview.
I tried
NSIndexPath *myIndexPath = [NSIndexPath indexPathForItem:myItem inSection:1];
[self.collectionView scrollToItemAtIndexPath:myIndexPath
atScrollPosition:UICollectionViewScrollPositionCenteredVertically
animated:NO];
But this gives back an arbitrary number and not relevant.
How can I do that?
I dont know details of code so i am generalising my answer.
You can have a unique property for myItem say ID.
If you are maintaining an array of items say : myItemArray, and populating collection view in same order then following can work:
NSArray* myItemArray; //array used to populate collectionView
NSIndexPath *myIndexPath; //this is what we need to know
int index = 0;
//myItem is object of item type & notifiedItem is notified item
for (Item* myItem in myItemArray) {
if (myItem.ID == notifiedItem.ID) {
myIndexPath = [NSIndexPath indexPathForItem:index inSection:1];//you got the index path right
break;
}
index++;
}
//use the index path