NSIndexPath return nil

Question

I have a UIViewController with a table view. Table row contains buttons which trigger an action.

//This is my button selector inside tableview delegate cellForRowAtIndexPath

[myBtn addTarget:self action:@selector(onButtonPress:event:)forControlEvents:UIControlEventTouchUpInside];

//This is button action



 -(void)onButtonPress:(UIButton*)sender {
       CGPoint buttonPosition = [sender convertPoint:CGPointZero toView:self.myTableView];
       NSIndexPath *indexPath = [self.myTableView indexPathForRowAtPoint:buttonPosition];

       DestinationViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:@"DestinationViewController"];
       controller.args=myArgs;
       [self.navigationController pushViewController:controller animated:YES];


 }

//this is my back button action

- (IBAction)onBackPressed:(id)sender {
     [self.navigationController popViewControllerAnimated:YES];
}

At first time all is working fine but after i navigated to other ViewController and return back to tableview controller by pressing back button and again click on table row button the NSIndexPath is nil

i have tried this indexPathForRowAtPoint returns nil only for first cell in a uitableview

score 0 · Answer 1 · answered Oct 28 '15 at 07:31

0

If I understand you correct, you have Buttons within TableViewCells and you don't get the IndexPath when you tap one of the buttons.

Of course is there no IndexPath since you never tapped a cell. Basically you ignore the complete tableview mechanism.

When creating the tableviewcell, tag the buttons with the index. Not the best approach, but will do.

answered Oct 28 '15 at 07:31

Helge Becker

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i said after i clicked on button which is inside my table row(myBtn) – Askarc Ali Oct 28 '15 at 08:10

score 0 · Answer 2 · answered Oct 28 '15 at 08:50

Set tag of button equal to indexPath.row and find the NSIndexPath from tag.

myBtn.tag=indexPath.row;
[myBtn addTarget:self action:@selector(onButtonPress:)forControlEvents:UIControlEventTouchUpInside];

-(void)onButtonPress:(UIButton*)sender {

UIButton *btnSender =(UIButton *)sender;

 NSIndexPath *indexPath = [NSIndexPath indexPathForRow:btnSender.tag inSection:0];

}

sahara108 · Answer 3 · 2015-10-28T14:25:03.360

0

I won't use the method indexPathForRowAtPoint: to get the indexPath. You can archive it with a different way. First add an UIView category:

Header file:

#import <UIKit/UIKit.h>

@interface UIView (TableCell)

-(UITableViewCell*)getTableCell;

@end

and implementation

@implementation UIView (TableCell)

-(UITableViewCell *)getTableCell
{
   while (self.superview) {
      if ([self.superview isKindOfClass:[UITableViewCell class]]) {
         return (UITableViewCell*)self.superview;
      }else {
         return [self.superview getTableCell];
      }
   }
   return nil;
}

Now, in your onButtonPress: you can do like this:

UITableViewCell *cell = [sender getTableCell];
NSIndexPath *indexPath = [self.tableView indexPathForCell:cell]

edited Oct 28 '15 at 14:25

answered Oct 28 '15 at 08:51

sahara108

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what is the different in this method – Askarc Ali Oct 28 '15 at 10:26
Your method is based on the view layout and it may not work if the view hasn't finished layout. This method guarantees to return an index whenever you have a cell. – sahara108 Oct 28 '15 at 10:32
i am new to iOS platform will you please explain how should i implement this. – Askarc Ali Oct 28 '15 at 10:43
this way now i am getting my cell UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier]; – Askarc Ali Oct 28 '15 at 10:44
this way i am getting button btn=(UIButton*)[cell viewWithTag:111]; – Askarc Ali Oct 28 '15 at 10:47
No it is wrong. I am on mobile right now so it is hard to edit the answer. You can search how to implement category in ios and try it. I will edit the answer when I am back my computer – sahara108 Oct 28 '15 at 10:48
A quick way to do is cell = sender.superView.superView.superView. – sahara108 Oct 28 '15 at 10:50
But it is for ios 7. You should try to call superView until you found the UITableViewCell – sahara108 Oct 28 '15 at 10:51
From how you get the button from the cell, it should be sender.superView to get back the cell – sahara108 Oct 28 '15 at 10:54
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/93598/discussion-between-sahara108-and-askarc-ali). – sahara108 Oct 28 '15 at 14:25

score 0 · Answer 4 · answered Oct 28 '15 at 09:16

0

My suggest you can write [tableView reload] under 'viewWillAppear'; Or use other way like block to implement

answered Oct 28 '15 at 09:16

jerry

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even i did it but no use – Askarc Ali Oct 28 '15 at 09:24

RStack · Accepted Answer · 2015-11-16T05:23:28.517

0

Try sending a delegate to the nextviewcontroller like

   DestinationViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:@"DestinationViewController"];
   controller.args=myArgs;
   controller.delegate = self;
   [self.navigationController pushViewController:controller animated:YES];

and when traversing back from that viewController to the present table viewcontroller pass that delegate.

This may help you...

edited Nov 16 '15 at 05:23

answered Nov 12 '15 at 09:31

RStack

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4
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thank you for your suggestion.how can i travers back ? can you give me sample?. because all my data in that should preserve. – Askarc Ali Nov 12 '15 at 10:55
Can you show me the code by which you are traversing to the present viewcontroller and the code by which you are showing the next viewcontroller – RStack Nov 13 '15 at 05:02
`controller.delegate = self;` add this line to your code – RStack Nov 16 '15 at 05:23

NSIndexPath return nil

5 Answers5