UITableViewCell format reused after deletion - ios

Question

I subclassed UITableViewCell. Basically what happens is that when you press the UITableViewCell drawing on the cell's layer occurs causing the cell to appear different. However, when I delete a cell, that drawing drops to the cell below it. This to me seems to indicate that the cell's format is getting re-used as would be normal. Thus I redrew the cell in CellForRowAtIndexPath as one can see below...
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
AGProgressViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
cell.textLabel.backgroundColor = [UIColor clearColor];
cell.detailTextLabel.backgroundColor = [UIColor clearColor];
//NSLog(#"progress value = %f", [cell.progress floatValue]);
if (!cell) {
cell = [[AGProgressViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
Task * task = nil;
if (indexPath.section == 0){
task = [self.tasksByDay[#"anyday"] objectAtIndex:indexPath.row];
} else if (indexPath.section == 1){
task = [self.tasksByDay[#"monday"] objectAtIndex:indexPath.row];
} else if (indexPath.section == 2){
task = [self.tasksByDay[#"tuesday"] objectAtIndex:indexPath.row];
} else if (indexPath.section == 3){
task = [self.tasksByDay[#"wednesday"] objectAtIndex:indexPath.row];
} else if (indexPath.section == 4){
task = [self.tasksByDay[#"thursday"] objectAtIndex:indexPath.row];
} else if (indexPath.section == 5){
task = [self.tasksByDay[#"friday"] objectAtIndex:indexPath.row];
} else if (indexPath.section == 6){
task = [self.tasksByDay[#"saturday"] objectAtIndex:indexPath.row];
} else if (indexPath.section == 7){
task = [self.tasksByDay[#"sunday"] objectAtIndex:indexPath.row];
}
cell.progress = [NSNumber numberWithFloat:([task.timeSpent floatValue]/[task.time floatValue])];
// this is calling the redrawing method in the cell
[cell drawFillInAtPercent:[task.timeSpent floatValue]/[task.time floatValue]];
//NSLog(#"progress value = %f vs. time spent = %f", [cell.progress floatValue], [task.timeSpent floatValue]/[task.time floatValue]);
cell.textLabel.text = task.name;
cell.detailTextLabel.text = [NSString stringWithFormat:#"%d minutes",
[task.time intValue] - [task.timeSpent intValue]];
return cell;
}
However, this did not fix the problem. All those NSLogs showed the cell being at the right level for every re-drawing. This means, for some reason, the cell that is getting deleted is not getting called in the cellForRowAtIndex path. The weird thing is that the text labels are changing, simply the custom drawing that I do in the UITableViewCell subclass is not changing.
This is the method that I am calling there in the subclass.
-(void) drawFillInAtPercent: (float) percent{
//if (percent > 0){
NSLog(#"progress layer at percent %f", percent);
_progressLayer = [CAGradientLayer layer];
_progressLayer.frame = CGRectMake(self.bounds.origin.x,
self.bounds.origin.y,
self.bounds.size.width * percent,
self.bounds.size.height);
_progressLayer.colors = #[(id)[[UIColor colorWithRed:0/255.0 green:0/250.0 blue:250.0/255.0 alpha:1.0f] CGColor],
(id)[[UIColor colorWithRed:150.0/200.0 green:150.0/200.0 blue:150.0/200.0 alpha:.5] CGColor],
(id)[[UIColor colorWithRed:200.0/200.0 green:200.0/200.0 blue:200.0/200.0 alpha:.5] CGColor],
(id)[[UIColor colorWithWhite:0.3f alpha:0.1f] CGColor]];
_progressLayer.locations = #[#0.00f, #0.2f, #0.90f, #1.00f];
[self.layer insertSublayer:_progressLayer atIndex:1];
//}
}
I have no idea what is happening, and I don't seem to be able to access the reused cell in order to redraw it.
These are the deletion methods:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
[self deactivateTimers];
NSArray * days = [NSArray arrayWithObjects: #"anyday", #"monday", #"tuesday", #"wednesday", #"thursday", #"friday", #"saturday", #"sunday", nil];
Task * task = self.tasksByDay[days[indexPath.section]][indexPath.row];
if ([task.weekly boolValue]){
task.finished = [NSNumber numberWithBool:1];
} else {
[managedObjectContext deleteObject:task];
}
[self.managedObjectContext save:nil];
[self grabTasksFromContext];
}
}
-(void) grabTasksFromContext{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"Task"
inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
NSError *error;
NSMutableArray * managedObjects = [NSMutableArray arrayWithArray:[managedObjectContext
executeFetchRequest:fetchRequest error:&error]];
int numObjects = [managedObjects count];
for (int i = 0; i < numObjects; i ++){
Task * task = [managedObjects objectAtIndex:i];
NSLog(#"name %#", task.name);
// if the task is finished we don't want it to be displayed in the list
if ([task.finished boolValue]){
NSLog(#"finished");
[managedObjects removeObject:task];
i -= 1;
numObjects -= 1;
}
}
self.tasks = managedObjects;
// This implementation is pretty ugly
// I'm sorry about that and will fix it in the future
// probably the more attractive way to do this is to make an array of the days, and then cycle through that and check through the array of tasks
monday = tuesday = wednesday = thursday = friday = saturday = sunday = anyday = 0;
NSMutableArray * mondayArray = [[NSMutableArray alloc] init];
NSMutableArray * tuesdayArray = [[NSMutableArray alloc] init];
NSMutableArray * wednesdayArray = [[NSMutableArray alloc] init];
NSMutableArray * thursdayArray = [[NSMutableArray alloc] init];
NSMutableArray * fridayArray = [[NSMutableArray alloc] init];
NSMutableArray * saturdayArray = [[NSMutableArray alloc] init];
NSMutableArray * sundayArray = [[NSMutableArray alloc] init];
NSMutableArray * anydayArray = [[NSMutableArray alloc] init];
for (Task * task in self.tasks){
if ([task.day isEqualToString:#"monday"]){
mondayArray[monday] = task;
monday++;
} else if ([task.day isEqualToString:#"tuesday"]){
tuesdayArray[tuesday] = task;
tuesday++;
} else if ([task.day isEqualToString:#"wednesday"]){
wednesdayArray[wednesday] = task;
wednesday++;
} else if ([task.day isEqualToString:#"thursday"]){
thursdayArray[thursday] = task;
thursday++;
} else if ([task.day isEqualToString:#"friday"]){
fridayArray[friday] = task;
friday++;
} else if ([task.day isEqualToString:#"saturday"]){
saturdayArray[saturday] = task;
saturday++;
} else if ([task.day isEqualToString:#"sunday"]){
sundayArray[sunday] = task;
sunday++;
} else {
anydayArray[anyday] = task;
anyday++;
}
}
self.tasksByDay = [[NSDictionary alloc] initWithObjectsAndKeys: mondayArray,#"monday",
tuesdayArray, #"tuesday", wednesdayArray, #"wednesday", thursdayArray, #"thursday",
fridayArray, #"friday", saturdayArray, #"saturday", sundayArray, #"sunday",
anydayArray, #"anyday", nil];
[self.tableView reloadData];
}
Any help or thoughts on what is happening would be appreciated.

Answer 1

However, when I delete a cell, that drawing drops to the cell below it.
This is the key observation: it indicates to me that at the time the redraw is happening, the model (i.e. your self.tasksByDay[dayName]) has not been updated yet. When a cell at a certain row is deleted, the taskByDay for the corresponding day needs to be updated to remove the corresponding row from the NSArray. If this does not happen, the data for the deleted task would influence the drawing of a cell at the next index, thus the visuals wold appear to "drop" by one row. From your description it sounds like this is precisely what is happening.
You need to make sure that by the time the table is refreshed (or the notification of a cell deletion is sent to the UITableView) the model has been updated already to not have the row being deleted. This way the table visuals would update as you expect them to.
Not directly related to the problem, but if you create an array
NSArray *dayName = #[#"anyday", #"monday", #"tuesday", #"wednesday", etc.];
you can replace the long chain of ifs with
task = [self.tasksByDay[dayName objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
The other problem in your code is that every time that you call drawFillInAtPercent:, a new CAGradientLayer is added. As you scroll up and down, reused cells accumulate new layers without ever getting rid of the previously added ones. You need to change your code to add the gradient layer only once, and then reusing the existing one inside your drawFillInAtPercent: method. For example, you can add the layer in the designated initializer of the AGProgressViewCell, assigning it to _progressLayer instance variable, and adding it to the layer hierarchy once. From then on, drawFillInAtPercent: would change the existing _progressLayer, rather than creating new ones each time.