CODEWITHSUNDEEP
iphoneobjective-cioscocoa-touchuikit
Chailie
Chailie

Reputation: 451

Why Wont NSIndexPath Work?

I was mading a simple demo with UITableView:When one cell is selected , show a tick in the cell and the last selected cell would be unticked , when run in simulator,it is good when select one cell for the first time,While if selected another cell,The application would be crushed without any log info, I didn't know what happened. Here is what i did in coding :

Header:

#import <UIKit/UIKit.h>   
@interface ViewController2 : UIViewController<UITableViewDataSource,UITableViewDelegate>
{
    NSIndexPath * oldIndexPath;
    NSArray *list;
}
@property(retain,nonatomic)NSIndexPath *oldIndexPath;
@property(strong,nonatomic)NSArray *list;
@end

Implementation:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell * cell = [tableView cellForRowAtIndexPath:indexPath];

    if(oldIndexPath == nil){
        cell.accessoryType = UITableViewCellAccessoryCheckmark;

    }else{
        UITableViewCell * oldCell = [tableView cellForRowAtIndexPath:oldIndexPath];
        oldCell.accessoryType = UITableViewCellAccessoryNone;
    }
    oldIndexPath = indexPath;
}

Any help is appreciated,Thanks

Upvotes: 0

Views: 140

Answers (2)

Siba Prasad Hota
Siba Prasad Hota

Reputation: 4789

Try This, Hope it will Work for you.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath


{

UITableViewCell * cell = [tableView cellForRowAtIndexPath:indexPath];


if(self.oldIndexPath != nil)

{

    UITableViewCell * oldCell = [tableView cellForRowAtIndexPath:self.oldIndexPath];
    oldCell.accessoryType = UITableViewCellAccessoryNone;
}

cell.accessoryType = UITableViewCellAccessoryCheckmark;



self.oldIndexPath = indexPath;

}

Upvotes: 0

jrturton
jrturton

Reputation: 119292

Always access your properties via self., don't access the ivar directly. By directly assigning you are bypassing any memory management used in the accessor methods, and when you later use the value, it has been released.

In the current version of Xcode, you don't need to declare ivars to back properties or use synthesize. This prevents you accidentally directly accessing the ivars.

Upvotes: 1

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