setObjectForKey: exception: object cannot be nil - ios

Question

I am building an app using Parse and Xcode. When using the Parse PFTableView I am getting the error:
Terminating app due to uncaught exception
'NSInvalidArgumentException', reason: '*** setObjectForKey: object
cannot be nil (key: classname)'
I understand that I am not setting the key somewhere in my code, but I do not know where and how to fix it.
#import "TableViewController.h"
#import <Parse/Parse.h>
#interface TableViewController ()
#end
#implementation TableViewController
- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
// This table displays items in the Todo class
self.parseClassName = #"Todo";
self.pullToRefreshEnabled = YES;
self.paginationEnabled = YES;
self.objectsPerPage = 25;
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Uncomment the following line to preserve selection between presentations.
// self.clearsSelectionOnViewWillAppear = NO;
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem;
self.parentViewController.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"red_bokeh.png"]];
self.tableView.backgroundColor = [UIColor clearColor];
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
}
- (void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Table view data source
#pragma mark - Parse
- (void)objectsDidLoad:(NSError *)error {
[super objectsDidLoad:error];
// This method is called every time objects are loaded from Parse via the PFQuery
}
- (void)objectsWillLoad {
[super objectsWillLoad];
// This method is called before a PFQuery is fired to get more objects
}
- (PFQuery *)queryForTable {
PFQuery *query = [PFQuery queryWithClassName:self.parseClassName];
// If no objects are loaded in memory, we look to the cache first to fill the table
// and then subsequently do a query against the network.
if (self.objects.count == 0) {
query.cachePolicy = kPFCachePolicyCacheThenNetwork;
}
[query orderByDescending:#"createdAt"];
return query;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath object:(PFObject *)object
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
// Configure the cell
cell.textLabel.text = object[#"text"];
cell.detailTextLabel.text = [NSString stringWithFormat:#"Priority: %#",
object[#"priority"]];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[super tableView:tableView didSelectRowAtIndexPath:indexPath];
}
#end
Here is the TableViewController.h:
#import <UIKit/UIKit.h>
#interface TableViewController : PFQueryTableViewController
#end

Answer 1

I solved this issue by following this Parse.com/help
I just change the method from initWithStyle to initWithCoder.
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self) {
// The className to query on
self.parseClassName = kPAPPhotoClassKey;
// Whether the built-in pull-to-refresh is enabled
self.pullToRefreshEnabled = YES;
// Whether the built-in pagination is enabled
self.paginationEnabled = YES;
// The number of objects to show per page
self.objectsPerPage = 10;
}
return self;
}

Answer 2

The variable self.parseclassname is never being set. If I had to guess, you are probably calling -init on the tableView instead of -initWithStyle
To fix it, in a super-temporary, dirty way, you should change this function in the following way:
- (PFQuery *)queryForTable {
if (!self.parseClassName) {
self.parseClassName = #"Todo";
}
PFQuery *query = [PFQuery queryWithClassName:self.parseClassName];
// If no objects are loaded in memory, we look to the cache first to fill the table
// and then subsequently do a query against the network.
if (self.objects.count == 0) {
query.cachePolicy = kPFCachePolicyCacheThenNetwork;
}
[query orderByDescending:#"createdAt"];
return query;
}