3_SimpleIndexedTableView/SimpleIndexedTableView/APLViewController.m

 
/*
     File: APLViewController.m
 Abstract: View controller that serves as the table view's data source and delegate. It uses the current UILocalizedIndexedCollation object to organize the time zones into appropriate sections, and also to provide information about section titles and section index titles.
 
  Version: 3.0
 
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#import "APLViewController.h"
#import "APLAppDelegate.h"
 
#import "APLTimeZoneWrapper.h"
 
// The sections array and the collation are private.
@interface APLViewController ()
@property (nonatomic) NSMutableArray *sectionsArray;
@property (nonatomic) UILocalizedIndexedCollation *collation;
- (void)configureSections;
@end
 
 
@implementation APLViewController
 
 
#pragma mark - Table view data source and delegate methods
 
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // The number of sections is the same as the number of titles in the collation.
    return [[self.collation sectionTitles] count];
}
 
 
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
 
    // The number of time zones in the section is the count of the array associated with the section in the sections array.
    NSArray *timeZonesInSection = (self.sectionsArray)[section];
 
    return [timeZonesInSection count];
}
 
 
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
 
    static NSString *CellIdentifier = @"MyIdentifier";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
 
    // Get the time zone from the array associated with the section index in the sections array.
    NSArray *timeZonesInSection = (self.sectionsArray)[indexPath.section];
 
    // Configure the cell with the time zone's name.
    APLTimeZoneWrapper *timeZone = timeZonesInSection[indexPath.row];
    cell.textLabel.text = timeZone.localeName;
 
    return cell;
}
 
 
/*
 Section-related methods: Retrieve the section titles and section index titles from the collation.
 */
 
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
    return [self.collation sectionTitles][section];
}
 
 
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {
    return [self.collation sectionIndexTitles];
}
 
 
- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index {
    return [self.collation sectionForSectionIndexTitleAtIndex:index];
}
 
 
#pragma mark - Set the data array and configure the section data
 
/*
 Configuring the sections is a little fiddly, and it's not directly relevant to understanding how sectioned table views themselves work, so there's no need to work though these methods if you don't want to.
 */
 
- (void)setTimeZonesArray:(NSMutableArray *)newDataArray {
    
    if (newDataArray != _timeZonesArray) {
        _timeZonesArray = [newDataArray mutableCopy];
        if (_timeZonesArray == nil) {
            self.sectionsArray = nil;
        }
        else {
            [self configureSections];
        }
    }
}
 
 
- (void)configureSections {
 
    // Get the current collation and keep a reference to it.
    self.collation = [UILocalizedIndexedCollation currentCollation];
 
    NSInteger index, sectionTitlesCount = [[self.collation sectionTitles] count];
 
    NSMutableArray *newSectionsArray = [[NSMutableArray alloc] initWithCapacity:sectionTitlesCount];
 
    // Set up the sections array: elements are mutable arrays that will contain the time zones for that section.
    for (index = 0; index < sectionTitlesCount; index++) {
        NSMutableArray *array = [[NSMutableArray alloc] init];
        [newSectionsArray addObject:array];
    }
 
    // Segregate the time zones into the appropriate arrays.
    for (APLTimeZoneWrapper *timeZone in self.timeZonesArray) {
 
        // Ask the collation which section number the time zone belongs in, based on its locale name.
        NSInteger sectionNumber = [self.collation sectionForObject:timeZone collationStringSelector:@selector(localeName)];
 
        // Get the array for the section.
        NSMutableArray *sectionTimeZones = newSectionsArray[sectionNumber];
 
        //  Add the time zone to the section.
        [sectionTimeZones addObject:timeZone];
    }
 
    // Now that all the data's in place, each section array needs to be sorted.
    for (index = 0; index < sectionTitlesCount; index++) {
 
        NSMutableArray *timeZonesArrayForSection = newSectionsArray[index];
 
        // If the table view or its contents were editable, you would make a mutable copy here.
        NSArray *sortedTimeZonesArrayForSection = [self.collation sortedArrayFromArray:timeZonesArrayForSection collationStringSelector:@selector(localeName)];
 
        // Replace the existing array with the sorted array.
        newSectionsArray[index] = sortedTimeZonesArrayForSection;
    }
 
    self.sectionsArray = newSectionsArray;
}
 
 
@end