TableView doesn't allow for 'section' in dictionary - objective-c

Question

I want to loop through a list of json items to use in my sectioned tableView. For this I would like to restructure the data to have a section->array setup, where array contains an array of sessions.
First of all, I don't know if this is the preferred way to go, there may be easier ways. I keep getting the error that I am not allowed to use 'section' as an identifier in the dictionary. Moreover, when I use something else than a 'section' the dictionary keeps getting overridden.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSString *day = _json[#"days"][3];
NSString *key;
NSUInteger count = 0;
NSMutableArray *sessionList = [[NSMutableArray alloc] init];
NSArray *timeslotsSorted = [[_json[#"schedule"][day] allKeys]
sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
NSArray *locationsSorted = [[_json[#"schedule"][day][timeslotsSorted[section]] allKeys]
sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
for (key in locationsSorted) {
NSDictionary *temp = _json[#"schedule"][day][timeslotsSorted[section]][key];
if ([temp isKindOfClass:[NSDictionary class]]) {
[sessionList addObject:temp[#"title"]]; //test array
count++;
}
}
_sessionDict = #{
section: sessionList
};
return count;
}

Answer 1

You are doing all the work to build your data structure in the wrong place. Lets say there are 10 sections in your data. This will call the tableView: numberOfRowsInSection method 10 times which makes this a pretty inefficient place to do much work. You will also have to implement the method that returns the number of sections to show, and the method to display each individual row.
I would build my data structures in the viewWillLoad method and then store it locallaly and reuse it in all the tableView methods.

Answer 2

First, this is what NSInteger is:
typedef int NSInteger;
You must wrap it into an object. Something like:
[NSNumber numberWithInteger:section]
And than add it to your dictionary.

Answer 3

i don't really know that your timeslotsSorted and locationsSorted contain right items, but lets say they do. I would recommend you to have this sorting before - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section and - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView; are called.
Lets say, you received JSON, so you have to parse it as you do, and then call [tableView reloadData] or reload visible cells with animations.
and then your tableView data source methods will be called and you will do something like:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [sessionList count];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSString* key = [self.sessionList objectAtIndex:section];
return [[self.secions objectForKey:key] count];
}
and don't forget to make strong properties for self.sections and self.sessionList