Dynamically sort NSMutableArray data into NSDictionary alphabetically [closed] - ios

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Unfortunatly I dont currently have internet on my laptop so I will have to describe my code, I have a mutable array of alphabetically sorted song titles. I have a uitableview that is currently displaying these however I want to have section heads and an alphabet index at the side of the table so I need to put these songs into an nsdictionary to display it, however I cant work out an an efficent method of sorting the array into the alphabetical sections (also has a # section, ive made a nsarray of section heads) in the nsdictionary.

Answer 1

There are many possibilities to prepare your data. But since your songs are already sorted your view controller could look something like this:
#interface TableViewController ()
#property (strong, nonatomic) NSArray *sectionTitles;
#property (strong, nonatomic) NSArray *songsInSections;
#end
#implementation TableViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSArray *songs = #[#"A song", #"Another song", #"Some other song", #"Yet another song"];
// store all the needed section titles
NSMutableArray *sectionTitles = [NSMutableArray array];
// store the songs in sections (arrays in array)
NSMutableArray *songsInSections = [NSMutableArray array];
// prepare the data for the table view
for (NSString *song in songs) {
// get the song's section title (first letter localized and uppercased)
NSString *sectionTitle = [[song substringToIndex:1] localizedUppercaseString];
// check if a section for the song's section title has already been created and create one if needed
if (sectionTitles.count == 0 || ![sectionTitle isEqualToString:sectionTitles[sectionTitles.count - 1]]) {
// add the section title to the section titles array
[sectionTitles addObject:sectionTitle];
// create an (inner) array for the new section
[songsInSections addObject:[NSMutableArray array]];
}
// add the song to the last (inner) array
[songsInSections[songsInSections.count - 1] addObject:song];
}
// "store" the created data to use it as the table view's data source
self.sectionTitles = sectionTitles;
self.songsInSections = songsInSections;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [self.songsInSections count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
return self.sectionTitles[section];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [self.songsInSections[section] count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
cell.textLabel.text = self.songsInSections[indexPath.section][indexPath.row];
return cell;
}
- (NSArray<NSString *> *)sectionIndexTitlesForTableView:(UITableView *)tableView {
return self.sectionTitles;
}
#end