Question

i have a question regarding NSUserDefaults. I am trying to save the checkmark that i place on a cell and then retrieve it when the app crashes or when user closes app and so on. I tried to use this post post as a guide, but no luck, but here’s what i have so far. The code from the post works, however, i only need one checkmark to be saved rather than many. How would i achieve this?

@implementation ClientsViewController

@synthesize clientsInt;        // This is just a variable that helps me do the drill down part of the rootviewcontroller
@synthesize checkedIndexPath;

- (NSString *)getKeyForIndex:(int)index
{
return [NSString stringWithFormat:@"KEY%d",index];
}

- (BOOL) getCheckedForIndex:(int)index
{
if([[[NSUserDefaults standardUserDefaults] valueForKey:[self getKeyForIndex:index]] boolValue]==YES)
{
    return YES;
}
else
{
    return NO;
}
}

- (void) checkedCellAtIndex:(int)index
{
BOOL boolChecked = [self getCheckedForIndex:index];

[[NSUserDefaults standardUserDefaults] setValue:[NSNumber numberWithBool:!boolChecked] forKey:[self getKeyForIndex:index]];
[[NSUserDefaults standardUserDefaults] synchronize];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];

    if([self getCheckedForIndex:indexPath.row]==YES)
    {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }
    else
    {
        cell.accessoryType = UITableViewCellAccessoryNone;
    }
}

// Configure the cell...
if (clientsInt == 0) {
    cell.textLabel.text = [array1 objectAtIndex:indexPath.row];
}
else if (clientsInt == 1) {
    cell.textLabel.text = [array2 objectAtIndex:indexPath.row];
}
else if (clientsInt == 2) {
    cell.textLabel.text = [array3 objectAtIndex:indexPath.row];
}
else if (clientsInt == 3) {
    cell.textLabel.text = [array4 objectAtIndex:indexPath.row];
}

if([self.checkedIndexPath isEqual:indexPath])
{
    cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
else
{
    cell.accessoryType = UITableViewCellAccessoryNone;
}

return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// Uncheck the previous checked row
if(self.checkedIndexPath)
{
    UITableViewCell* uncheckCell = [tableView cellForRowAtIndexPath:self.checkedIndexPath];
    uncheckCell.accessoryType = UITableViewCellAccessoryNone;
}
UITableViewCell* cell = [tableView cellForRowAtIndexPath:indexPath];
cell.accessoryType = UITableViewCellAccessoryCheckmark;
self.checkedIndexPath = indexPath;

[self checkedCellAtIndex:indexPath.row];

if([self getCheckedForIndex:indexPath.row]==YES)
{
    cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
else
{
    cell.accessoryType = UITableViewCellAccessoryNone;
}

[tableView deselectRowAtIndexPath:indexPath animated:YES];
}

Answer 1

Maybe try something like this every time the user checks a row:

[[NSUserDefaults standardUserDefaults] setValue:[NSNumber numberWithInt:index] forKey:@"kCheckedBoxKey"];

Since each time, you would save the index under the same key (@”kCheckedBoxKey”), only one index will ever be stored, and it will always be the latest one that the user checked. All you would need to do the next time you load is ask userDefaults if it can find a value for the key @”kCheckedBoxKey”, and if so, you would respond by programatically checking the index that was stored.

(you’d of course also want to clean it up by using #define CHECKED_KEY @"kCheckedBoxKey" at the top of the file, and use CHECKED_KEY instead of the literal string to protect against misspellings. At any rate, the point is to make sure you always save & restore using that same key.)