How to keep selection of untouched cells intact? - objective-c

Question

I have a tableView where I select cells and add the data in an array, I also have the option of swiping and then deleting a particular cell which eventually deletes the data from the array.
The problem is that once I delete a row, I lose all my selection state after I reload the table,
For that I checked again with the selection array and reselected all these cells,
BUT I am stuck at one place, Much before I actually delete a cell and reload the tableView, as soon as I swipe over a cell, selection state of all other cells also go away.
NOTE: I have two arrays, one with list of itmes to be displayed in the tableView and one with the selected items.
Here is some code:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 50;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [self.contactList count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *MyIdentifier = #"MyIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:MyIdentifier] autorelease];
}
cell.selectionStyle = UITableViewCellSelectionStyleGray;
[cell.textLabel setTextColor:[UIColor colorWithRed:103.0/255.0 green:103.0/255.0 blue:103.0/255.0 alpha:1.0]];
[cell.textLabel setFont:[UIFont fontWithName:#"ITCAvantGardeStd-Bk" size:14.0]];
if (![[[self.contactList objectAtIndex:indexPath.row] objectForKey:#"nickName"] isEqualToString:#""])
cell.textLabel.text = [NSString stringWithFormat:#"%#",[[self.contactList objectAtIndex:indexPath.row] objectForKey:#"nickName"]];
else
cell.textLabel.text = [NSString stringWithFormat:#"%# %#",[[self.contactList objectAtIndex:indexPath.row] objectForKey:#"firstName"],[[self.contactList objectAtIndex:indexPath.row] objectForKey:#"lastName"]];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"Selected cell index==>%d\n",indexPath.row);
//NSString *emailID = [NSString stringWithFormat:#"%#",[[self.contactList objectAtIndex:indexPath.row] objectForKey:#"email_key"]];
NSLog(#"emailID==>%#\n",[self.contactList objectAtIndex:indexPath.row]);
[self.emailShareList addObject:[self.contactList objectAtIndex:indexPath.row]];
//[self.emailShareList insertObject:emailID atIndex:indexPath.row];
NSLog(#"Array value==>%#\n",self.emailShareList);
//[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"deSelected cell index==>%d\n",indexPath.row);
NSString *emailID = [NSString stringWithFormat:#"%#",[[self.contactList objectAtIndex:indexPath.row] objectForKey:#"email_key"]];
NSLog(#"emailID==>%#\n",emailID);
[self.emailShareList removeObject:[self.contactList objectAtIndex:indexPath.row]];
NSLog(#"deSelect row Array value==>%#\n",self.emailShareList);
}
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete)
{
if(indexPath.row != 0)
{
NSString *contactID = [[self.contactList objectAtIndex:indexPath.row] objectForKey:#"contactId"];
NSLog(#"content on delete row==>%#\n",contactID);
[self.contactList removeObjectAtIndex:indexPath.row];
[self deleteContactToServer:contactID];
}
}
[contactTableView reloadData];
for (int i = 0; i < [self.emailShareList count]; i++)
{
for (int j = 0; j < [self.contactList count]; j++)
{
if([[[self.contactList objectAtIndex:j] valueForKey:#"email"] isEqualToString: [[self.emailShareList objectAtIndex:i] valueForKey:#"email"]])
{
NSIndexPath *path1 = [NSIndexPath indexPathForRow:j inSection:0];
[contactTableView selectRowAtIndexPath:path1 animated:NO scrollPosition:UITableViewScrollPositionNone];
}
}
}
}
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCellEditingStyle style = UITableViewCellEditingStyleNone;
if(indexPath.row != 0)
style = UITableViewCellEditingStyleDelete;
return style;
}

Answer 1

When you delete an item, you don't necessary have to reload the entire tableview. You could use the – deleteRowsAtIndexPaths:withRowAnimation: method to just remove the cell in question (along with an according model update). This will probably retain your selection.
To keep your selections when entering editing mode (swipe for delete is a special case of editing mode as well) you nee to do two things:
First, enable allowsSelectionDuringEditing on your tableView:
self.tableView.allowsSelectionDuringEditing = YES;
Second, create a UITableView subclass and override setEditing:animated: like this:
- (void)setEditing:(BOOL)editing animated:(BOOL)animated {
NSArray *indexPaths = self.indexPathsForSelectedRows;
[super setEditing:editing animated:animated];
for (NSIndexPath *ip in indexPaths) {
[self selectRowAtIndexPath:ip animated:NO scrollPosition:UITableViewScrollPositionNone];
}
}
Personally, I would rather use some sort of custom selection mechanism, when selections are important from a model point of view. I would create a custom cell subclass, add a selection property to it let it change the cell styling accordingly. The build-in features that affect regular table view selections won't cause problems with such an approach.

Answer 2

Here is an additional method of preserving table selections in and out of edit mode without having to subclass UITableView. Add the following to your UITableViewControllerView.
Within viewDidLoad add:
self.tableView.allowsSelectionDuringEditing = YES;
Then override setEditing:animated:
- (void)setEditing:(BOOL)editing animated:(BOOL)animate
{
NSArray *selectedIndexPaths = [self.tableView indexPathsForSelectedRows];
[super setEditing:editing animated:animate];
for (NSIndexPath *selectedIndexPath in selectedIndexPaths) {
[self.tableView selectRowAtIndexPath:selectedIndexPath animated:NO scrollPosition:UITableViewScrollPositionNone];
}
}