iOS - Pagination using a Dictionary based UITableView - ios

Question

I'm building an iOS application which has a tableview with multiple sections.
The sections depends on the number of keys on an NSMutableDictionary.
I'm trying to make pagination by adding data to that dictionary every time I reach the last cell of the row.
My problem is that the pagination event is fired multiple times and makes the sections look in different order. I guess the last problem is because of the method I'm using to add new data is addEntriesFromDictionary.
So basically my questions are:
- Is the Dictionary data source approach a proper one? Should I change it for an Array data source one?
- Causes of the multiple pagination calls issue
Here's my code so far:
#implementation FooViewController
- (void)viewDidLoad {
self.FooStore = [[FooStore alloc]init];
[self.FooStore getFooDTO: #1];
[self setNavigationBar:nil];
[self setNeedsStatusBarAppearanceUpdate];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(handleFooDTOChange:)
name:#"FooDTOChanged"
object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(handleLoadDataFoo:)
name:#"loadDataFoo"
object:nil];
self.activityView = [[UIActivityIndicatorView alloc]
initWithActivityIndicatorStyle: UIActivityIndicatorViewStyleGray];
self.activityView.center = self.view.center;
[self.activityView startAnimating];
[self.view addSubview:self.activityView];
}
- (void)handleFooDTOChange:(NSNotification *)note {
NSDictionary *theData = [note userInfo];
if (theData != nil) {
FooDTO *FooDTO = theData[#"FooDTO"];
if(FooDTO.date != nil){
[self setNavigationBar:FooDTO.date];
[self.activityView stopAnimating];
}
}
}
- (void)handleLoadDataFoo:(NSNotification *)note {
NSDictionary *theData = [note userInfo];
if (theData != nil) {
[self.FooStore getFooDTO: theData[#"paginaActual"]];
}
}
… some code ..
#end
Table View Controller:
#implementation FooTableViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.currentPage = 1;
self.data = [[NSMutableDictionary alloc] init];
[self.tableView setHidden:YES];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(handleFooDTOChange:)
name:#"FooDTOChanged"
object:nil];
}
- (void)handleFooDTOChange:(NSNotification *)note {
NSDictionary *theData = [note userInfo];
if (theData != nil) {
FooDTO *FooDTO = theData[#"FooDTO"];
if ([[FooDTO.dataFoo allKeys] count] > 0){
[self.data addEntriesFromDictionary: FooDTO.dataFoo];
[self.tableView setHidden:NO];
[self.tableView reloadData];
}
}
}
-(void) dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return self.data.allKeys.count;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
NSString *arrayKey = [self.data.allKeys objectAtIndex:section];
NSArray *a = [self.data objectForKey:arrayKey];
return a.count;
}
-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *arrayKey = [self.data.allKeys objectAtIndex:indexPath.section];
NSArray *dataKey = [self.data objectForKey:arrayKey];
if(indexPath.row == [dataKey count] -1 && indexPath.section == [self.data.allKeys count] - 1){
self.currentPage++;
NSDictionary *dataDictionary = #{
#"currentPage": [NSNumber numberWithInt: self.currentPage]
};
[[NSNotificationCenter defaultCenter] postNotificationName:#"loaddataFoo" object:self userInfo:dataDictionary];
}
}
Service:
#implementation FooStore
- (FooDTO *) getFooDTO: (NSNumber *) page
{
FooDTO *FooDTO =[[FooDTO alloc]init];
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
NSString *dateStr = [dateFormat stringFromDate:date];
NSDictionary *parameters = #{
//urlparameters
};
[manager POST:#"http://my.service/foos.json" parameters:parameters
success:^(AFHTTPRequestOperation *operation, id responseObject) {
//handle data
}
NSDictionary *dataDictionary = #{
#"FooDTO": FooDTO
};
[[NSNotificationCenter defaultCenter] postNotificationName:#"FooDTOChanged" object:self userInfo:dataDictionary];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
NSDictionary *dataDictionary = #{
#"error": error
};
[[NSNotificationCenter defaultCenter] postNotificationName:#"FooError" object:self userInfo:dataDictionary];
}
];
return nil;
};
#end

Answer 1

Dictionaries are unordered collections. The sections and rows in a table view must be served up in the same order every time the table view asks for information, so dictionaries are not suitable.
It's pretty common to use a single NSArray or NSMutableArray for a single-section table view, or an array of arrays for a multi-sectioned table view. (The outer array contains your sections and the inner arrays contain the rows for each section.
You can make the data for each cell a dictionary if that's helpful (So you would have an array of arrays of dictionaries.) That way each key/value pair in the inner dictionary contains different information that you need to display in your cells.
I would suggest NOT using a dictionary to represent the cell in your table view. (But as noted you CAN use a dictionary to save the different settings for a cell.)