Updating Table View with items from singleton class - ios

Question

I'm new to Objective-C and iOS programming, using storyboards.
Scene 1: Contains a Table View. (ViewController.m)
Displaying a Table View populated by NSMutableArray from a singleton class.
Add button -> Scene 2.
Scene 2: Create and add object. (AddObjectViewController.m)
Creating and saving a custom object to NSMutableArray in a singleton class to access it from different Scenes/View Controllers.
Save button -> Scene 1.
Cancel button -> Scene 1.
Problem
Upon return to Scene 1, the Table View is blank.
At the time of - (void)viewDidLoad in Scene 1 (ViewController.m, where table is populated), array in singleton class is indeed empty.
However, shortly after, the array do contain the newly created object.
Leaving Scene 1 and returning to it will update the Table View and list the object that was just added.
It appears more time is needed to write data before initializing singleton class in ViewController.
To that end, I tried to add Wait/Sleep time after writing to the array in Scene 2 (AddObjectViewController.m) and before initializing singleton class in Scene 1 (ViewController.m).
It does not work. Seems like everything sleeps.
What to do? It should already be working by my logic, and from my research, a singleton class should be perfect for this scenario.
Edit: The important code.
Code
ViewController2.m
- (IBAction)saveButtonPressed:(id)sender {
// Custom initialization.
Computer *object = [[Computer alloc] initWithName:nameField.text IP:ipField.text Port:portField.text Password:passwordField.text];
// Add Computer to array of Computers via "Singleton" (shared array).
Computers *sharedComputers = [Computers sharedComputers];
[sharedComputers addComputer:object];
}
ViewController.m
#implementation ViewController{
NSMutableArray *tableData;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *tableIdentifier = #"TableItem";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:tableIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:tableIdentifier];
}
cell.textLabel.text = [tableData objectAtIndex:indexPath.row];
cell.imageView.image = [UIImage imageNamed:#"Computer Filled-25.png"];
return cell;
}
- (void)viewDidLoad {
[super viewDidLoad];
// Initialize table data
tableData = [[NSMutableArray alloc] init];
// Add objects to table
Computers *sharedComputers = [Computers sharedComputers];
for (Computer* item in [sharedComputers getArray]) {
[tableData addObject:item.name];
}
}
Computers.m (Singleton class)
- (void)addComputer:(Computer *)aComputer {
[computerArray addObject:aComputer];
}

Answer 1

If you are filling your dataSource array of table view in Scene 1 in viewDidLoad method then you need to know that viewDidLoad will not be called again once you return back to Scene 1 from Scene 2. The solution is to move the dataSource implementation to viewWillAppear method in Scene 1
-(void)viewDidLoad{
[super viewDidLoad];
dataSource = [[NSMutableArray alloc]init];
}
-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
[dataSource removeAllObjects];
dataSource = singletonClass.MutableArray; // fill dataSource from your singleton class
}
This will make sure your tableview data is refreshed every time you view Scene1