How do i get numberOfRowsInSection from nested NSMutableDictionary? - ios

Question

I am trying to follow this post http://www.appcoda.com/ios-programming-index-list-uitableview/ to create sections using UITableViewController.
I am using two NSMutableDictionaries first(_curatedItemDictionary) dictionary is to store key value pairs from Parse and second (_sectionsDictionary) is to store these in dictionary as key and values as Category type.
[_sectionsDictionary setObject:[obj objectForKey:#"Category"] forKey:_curatedItemDictionary];
I did this because i couldn't store the key as category and value as dictionary as dictionaries will not support duplicate keys.
I am getting numberOfSectionsInTableView by using the below code
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
for(NSString *key in [_sectionsDictionary allKeys]) {
[_cleanArray addObject:[_sectionsDictionary objectForKey:key]];
}
NSCountedSet *set = [[NSCountedSet alloc] initWithArray:_cleanArray];
for (id item in set) {
NSInteger count = (unsigned long)[set countForObject:item];
[_rowForIndexArray addObject:[NSNumber numberWithInteger:count]];
}
_cleanSectionArray = [[NSSet setWithArray:_cleanArray] allObjects];
return [_cleanSectionArray count];
}
How do i get numberOfRowsInSection from the above information ? How do i know which items are being iterated for a particular section ?
Here is the code I am using to create curatedItemDictionary from Parse.com data
PFQuery *query = [PFQuery queryWithClassName:[NSString stringWithString:self.classname]];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
// The find succeeded.
for (PFObject *obj in objects) {
self.curatedItemDictionary = [[NSMutableDictionary alloc]init];
[_curatedItemDictionary setValue:[obj objectForKey:#"ItemName"] forKey:#"ItemName"];
[_curatedItemDictionary setValue:[obj objectForKey:#"Price"] forKey:#"Price"];
[_sectionsDictionary setObject:[obj objectForKey:#"Category"] forKey:_curatedItemDictionary];
[self.tableView reloadData];
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];

Answer 1

Based on the code provided in the comment to the original post something similar to that, just an alternative:
self.sectionsDictionary = [NSMutableDictionary new];
NSMutableArray *sectionsArray;
for (PFObject *obj in objects) {
sectionsArray = [self.sectionsDictionary objectForKey: [obj objectForKey:#"Category"]];
if (nil == sectionsArray) sectionsArray = [NSMutableArray new];
[sectionsArray addObject: obj]
[self.sectionsDictionary setObject: sectionsArray forKey: [obj objectForKey:#"Category"]];
}
Then in your numberOfSectionsInTableView you can get the amount of sections just by accessing count method on NSMutableDictionary
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return [self.sectionsDictionary count];
}
And then if you need number of rows in each particular section:
- (NSInteger) tableView:(UITableView*)tableView numberOfRowsInSection:(NSInteger)section
{
NSArray *keys = [self.sectionsDictionary allKeys];
id aKey = [keys objectAtIndex:section];
NSMutableArray *arr = [self.sectionsDictionary objectForKey:aKey];
return (arr) ? arr.count : 0;
}
But of course you can loop through the keys in your sectionsDictionary when preparing the datasource and put section index with some key, so you do not need to do use the allKeys trick.