Displaying data retrieved from Parse in UITableView - objective-c

Question

After all progress i made with your answers, my issue changed. So i am changing my question with clearer way. I have an UITableView which is showing my retrieved data from Parse.com. So i made a NSMutableArray for adding objects to that array when they are retrieved. But my problem is even i add objects to NSMutableArray, my table does not show anything but default screen of UITableView. I thing the issue is UITableView is formed before my NSMutableArray got its objects. Here is my code:
Note: The PropertyClass is the class which has the properties of my objects.
At MyTableViewController.h
#interface MyTableViewController : UITableViewController <CLLocationManagerDelegate> {
PFObject *object;
}
#property (strong, nonatomic) IBOutlet UITableView *MyTableView;
#end
At UITableViewController.m
#interface MyTableViewController ()
#property(strong)NSMutableArray *myNSMutableArray;
#end
#implementation MyTableViewController
#synthesize myNSMutableArray,MyTableView;
-(void) retrievingDataFromParse{
PFQuery *query = [PFQuery queryWithClassName:#"MyObjectsClass"];
[query whereKey:#"ObjectsNumber" lessThanOrEqualTo:10];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
// The find succeeded.
NSLog(#"Successfully retrieved %d scores.", objects.count);
if (objects.count==0) {
NSString *objectError = #"There no object retrieved from Parse";
PropertiesClass *PC = [[PropertiesClass alloc]initWithPropert1:objectError Propert2:nil Propert3:nil Propert4:nil];
[myNSMutableArray addObject:PC];
}
for (int i = 0; i < objects.count; i++) {
object = [objects objectAtIndex:i];
NSString *Propert1 = [object objectForKey:#"Propert1"];
NSNumber *Propert2 = [object objectForKey:#"Propert2"];
NSNumber *Propert3 = [object objectForKey:#"Propert3"];
NSString *Propert4 = [object objectForKey:#"Propert4"];
PropertiesClass *PC = [[PropertiesClass alloc]initWithPropert1:Propert1 Propert2:Propert2 Propert3:Propert3 Propert4:Propert4];
[myNSMutableArray addObject:PC];
};
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.myNSMutableArray = [NSMutableArray array];
[self retrievingDataFromParse];
[MyTableView reloadData];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [myNSMutableArray count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
PropertiesClass *PC= [myNSMutableArray objectAtIndex:indexPath.row];
cell.textLabel.text=PC.Propert1;
return cell;
}

Answer 1

Looking at your code i see that you never create a UITableViewCell, you should change this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
PropertyClass *PC = [myMutableArray objectAtIndex:indexPath.row];
cell.textLabel.text = PC.x;
return cell;
}
with this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if (nil == cell){
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
PropertyClass *PC = [myMutableArray objectAtIndex:indexPath.row];
cell.textLabel.text = PC.x;
return cell;
}
the method dequeueReusableCellWithIdentifier:forIndexPath: return a UITableViewCell only if there are unused, but already allocated, cells in your table view. otherwise it returns nil.
Also when you update the mutable array containing all your data you should call [yourTableView reloadData] to force the table view to reload its content.

Answer 2

Your code is quite cryptic. Few suggestions here.
First, rename variables and methods with camelCaseNotation (camel case notation). For example, MyMutableArray should be myMutableArray. RetrievingDataFromParse should be retrievingDataFromParse (and so on). Start upper case letter are for classes.
Second, what does this code mean (I put comment on your code)?
for (int i = 0; i < objects.count; i++) {
// where do you have defined object?
object = [objects objectAtIndex:i];
NSString *x = [object objectForKey:#"x"];
NSNumber *y = [object objectForKey:#"y"];
NSNumber *z = [object objectForKey:#"z"];
NSString *t = [object objectForKey:#"t"];
// is Mekan a subclass of PropertiyClass or what else?
PropertiyClass *Properties = [[Mekan alloc]initWithx:x y:y z:z t:t]
// what's MekanKalibi? Maybe you need to add Properties
[MyMutableArray addObject:MekanKalibi];
}
Edit
If you don't use iOS6 - (void)registerClass:(Class)cellClass forCellReuseIdentifier:(NSString *)identifier you should alloc-init cells.
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if(!cell) {
// alloc-init a new cell here...
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
// or if you don't use ARC
// cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
PropertyClass *PC = [myMutableArray objectAtIndex:indexPath.row];
cell.textLabel.text = PC.x;
return cell;
Edit 2
I don't know how parse works but I suppose it manages async requests. So, at the end of your for loop, just call reload data in the table.

Answer 3

Parse states:
The InBackground methods are asynchronous, so any code after this will run immediately. Any code that depends on the query result should be moved inside the completion block above.
I had the same problem. When you reload the table, you need to move it so it is inside the block. Worked for me.
I'm not 100% sure how the asynchronous parts affect it so. I know that the start of my viewDidload and the end occured then this block, hence the problem.
People should probably up this as this solves the issue.
Cheers.

Answer 4

All you have to do is reload tableView in the block... this will show data.
for (int i = 0; i < objects.count; i++) {
object = [objects objectAtIndex:i];
NSString *Propert1 = [object objectForKey:#"Propert1"];
NSNumber *Propert2 = [object objectForKey:#"Propert2"];
NSNumber *Propert3 = [object objectForKey:#"Propert3"];
NSString *Propert4 = [object objectForKey:#"Propert4"];
PropertiesClass *PC = [[PropertiesClass alloc]initWithPropert1:Propert1 Propert2:Propert2 Propert3:Propert3 Propert4:Propert4];
[myNSMutableArray addObject:PC];
};
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
**[MyTableView reloadData];**
}];