Why can't I place my NSDictionary data into a UITableView - ios

Question

I am have an NSDictionary which multiple dictionaries like this:
{
complete = 0;
description = Description;
"due_date" = "2014-02-28 16:30:03";
name = Task;
priority = 2;
"task_id" = 1;
"user_id" = 1;
},
{
complete = 0;
description = "";
"due_date" = "0000-00-00 00:00:00";
name = "";
priority = 0;
"task_id" = 2;
"user_id" = 1;
}
I would like to display each instance of "name" in my UITableView
I have tried this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = nil;
for (task in tasks) {
cell.textLabel.text = [[task objectAtIndex:indexPath.row] valueForKey:#"name"];
}
return cell;
}
But the app crashes each time I attempt to do run it.
What am I doing wrong?
Here is the error I get:
Assertion failure in -[UITableView _configureCellForDisplay:forIndexPath:]

Answer 1

Change your code to look like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = nil;
cell.textLabel.text = [[tasks objectAtIndex:indexPath.row] valueForKey:#"name"];
return cell;
}
The problem was that task was a dictionary, so it didn't respond to objectAtIndex:.
BTW, you need to create or dequeue a UITableViewCell instance as well, but I simply corrected your crashing issue for you.

Answer 2

The reason you are getting a crash is because you are returning nil from tableView:cellForRowAtIndexPath:.
I think you are also misunderstanding how this table view data source method works. It gets called once per table cell in your table (hence why you return a UITableViewCell from it...). You don't need to be looping over your data collection inside it - you should be getting the correct data object from your collection based on the indexPath.
On top of that, as others have said, if tasks is in fact an NSDictionary, then it won't respond to objectAtIndex. In all likelihood, you probably want your data collection to be an NSArray, if it isn't already.
Edit:
Judging by the error you are getting, tasks is in fact an NSArray (as the error is caused by returning nil from tableView:cellForRowAtIndexPath:). Try the following:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"MyCellIdentifier" forIndexPath:indexPath];
NSDictionary *task = [tasks objectAtIndex:indexPath.row];
cell.textLabel.text = [task objectForKey:#"name"];
return cell;
}
Edit 2:
Also, you should be using objectForKey: instead of valueForKey:.

Answer 3

Dictionaries don't have indices.
You can't call a objectAtIndex: method on a dictionary, that's why your app is crashing. Instead, you need to use objectForKey: with the appropriate key to get the value you want.

Answer 4

Try storing those NSDictionary's in an NSArray. An NSArray will allow you to hold them, along with accessing objects with "objectAtIndex".
If you need to add NSDictionary's at run-time, try using an NSMutableArray, which allows you to add and remove array objects when needed.