How to reload custom table view cell after last row deletion? - ios

Question

I have a UITableView with a simple array as data source. I designed a custom nib for a special UITableViewCell that is shown when the array is empty (i.e. when the app first starts).
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
if ([self.wallet count] == 0)
return 1;
else return [self.wallet count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// If there isn't any coupon yet, then show the custom "No Coupon Yet" cell
if ([self.wallet count] == 0)
return [tableView dequeueReusableCellWithIdentifier:#"NoCouponCell" forIndexPath:indexPath];
else {
CouponCell *cell = [tableView dequeueReusableCellWithIdentifier:#"CouponCell" forIndexPath:indexPath];
Coupon *coupon = [self.wallet objectAtIndex:indexPath.row];
[cell configureForCoupon:coupon];
return cell;
}
}
Since I'd like to add the swipe-to-delete functionality, I provided the following method for the view controller.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
[self.wallet removeObjectAtIndex:indexPath.row];
// Creates a new, temporary array holding just the one index-path item
NSMutableArray *tmp = [[NSMutableArray alloc] initWithObjects:indexPath, nil];
// Tells the table view to delete the row with a nice animation
[tableView deleteRowsAtIndexPaths:tmp withRowAnimation:UITableViewRowAnimationAutomatic];
}
However, when the table view has only one row and I try to delete it, my app crashes. Why?
EDIT: The debug info tells that a NSInternalInconsistencyException is raised.

Answer 1

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete)
{
// Delete the row from the data source
[self.wallet removeObjectAtIndex:indexPath.row];
[tableView reloadData]; // reload your table to see updates
// or if you what some animation use|
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath]
withRowAnimation:UITableViewRowAnimationAutomatic];
...
Here's a fix for your cellForRowAtIndexPath:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
CouponCell *cell = [tableView dequeueReusableCellWithIdentifier:[self.wallet count] == 0 ? #"NoCouponCell" : #"CouponCell" forIndexPath:indexPath];
if ([self.wallet count] > 0)
{
Coupon *coupon = [self.wallet objectAtIndex:indexPath.row];
[cell configureForCoupon:coupon];
}
return cell;
}

Answer 2

try this in your code:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [self.wallet count];
}

Answer 3

You are returning a rowcount of 1 if your data array wallet has no elements:
if ([self.wallet count] == 0)
return 1;
else return [self.wallet count];
But in the commitEditingStyle method you don't handle this case: This means that it's possible to delete the NoCouponCell. And I assume that the crash occurs, because you want to remove an object from your data-array which does not exist.
[self.wallet removeObjectAtIndex:indexPath.row];
Solution: Use the following delegate method to determine when a cell can be edited: This prevents the delegate method commitEditingStyle to be called.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath{
return [self.wallet count] > 0
}

Answer 4

Try this piece of code:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
[self.wallet removeObjectAtIndex:indexPath.row];
// Creates a new, temporary array holding just the one index-path item
NSMutableArray *tmp = [[NSMutableArray alloc] initWithObjects:indexPath, nil];
// Tells the table view to delete the row with a nice animation
[tableView beginUpdates];
[tableView deleteRowsAtIndexPaths:tmp withRowAnimation:UITableViewRowAnimationAutomatic];
[tableView endUpdates];
}

Answer 5

Use this in your numberOfRowsInSection function:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [self.wallet count];
}
And at the end of your commitEditingStyle function, use
[tableView reloadData];

Answer 6

you can add a view to the UITableview tableFooterView on tableview datasource, you can put your custome cell'content in this view
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
if (dataArray.count == 0) {
UIView *view = [[UITableView alloc] initWithFrame:self.view.bounds];
view.backgroundColor = [UIColor blueColor];
self.tableView.tableFooterView = view;
}
return dataArray.count;
}