UITableView with Section, IndexList and Search - ios

Question

I have added my delegate method and
I have a UITableView with a list of names. It has sections with an alphabetical index on the right hand side (see picture).
My program crashes whenever I enter a first character in the search field. I get the following error:
UpdateSearchResultsForSearchController
[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'
Understand I am trying to access an empty array, in the method UpdateSearchResultsForSearchController.
The program crashes in the last line of the method.
[((UITableViewController *)self.searchController.searchResultsController).tableView reloadData];
Here is the header
#import <UIKit/UIKit.h>
#import "EmployeeDatabase.h"
#interface EmployeeListViewController : UITableViewController<UISearchResultsUpdating, UISearchBarDelegate>
#property (nonatomic, strong) NSMutableArray *employees;
#property (nonatomic, strong) UISearchController *searchController;
#property (nonatomic, strong) NSMutableArray *tableSections;
#property (nonatomic, strong) NSMutableArray *tableSectionsAndItems;
#end
and here is the implementation
#import "EmployeeListViewController.h"
#import "EmployeeDetailViewController.h"
#implementation EmployeeListViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self initializeTableContent];
[self initializeSearchController];
[self styleTableView];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
#pragma mark - Initialization methods
- (void)initializeTableContent {
self.employees = [EmployeeDatabase getEmployees];
self.tableSections = [NSMutableArray array];
self.tableSectionsAndItems = [NSMutableArray array];
for (employee *name in self.employees) {
NSString *key = [[name.lstNme substringToIndex: 1] uppercaseString];
if ([self.tableSections containsObject:key] == false) {
[self.tableSections addObject:key];
NSMutableArray *tmpArray = [NSMutableArray array];
[tmpArray addObject:name.fulNme];
NSMutableDictionary *tmpDictionary = [NSMutableDictionary dictionaryWithObject:tmpArray forKey:key];
[self.tableSectionsAndItems addObject:tmpDictionary];
} else {
NSMutableArray *tmpArray = [NSMutableArray array];
NSUInteger index = [self.tableSections indexOfObject:key];
NSMutableDictionary *tmpDictionary = [self.tableSectionsAndItems objectAtIndex:index];
tmpArray = [tmpDictionary objectForKey:key];
[tmpArray addObject:name.fulNme];
[self.tableSectionsAndItems removeObjectAtIndex:index];
[self.tableSectionsAndItems addObject:tmpDictionary];
}
}
}
- (void)initializeSearchController {
//instantiate a search results controller for presenting the search/filter results (will be presented on top of the parent table view)
UITableViewController *searchResultsController = [[UITableViewController alloc] initWithStyle:UITableViewStylePlain];
searchResultsController.tableView.dataSource = self;
searchResultsController.tableView.delegate = self;
//instantiate a UISearchController - passing in the search results controller table
self.searchController = [[UISearchController alloc] initWithSearchResultsController:searchResultsController];
//this view controller can be covered by theUISearchController's view (i.e. search/filter table)
self.definesPresentationContext = YES;
//define the frame for the UISearchController's search bar and tint
self.searchController.searchBar.frame = CGRectMake(self.searchController.searchBar.frame.origin.x,
self.searchController.searchBar.frame.origin.y,
self.searchController.searchBar.frame.size.width, 44.0);
self.searchController.searchBar.tintColor = [UIColor whiteColor];
//add the UISearchController's search bar to the header of this table
self.tableView.tableHeaderView = self.searchController.searchBar;
//this ViewController will be responsible for implementing UISearchResultsDialog protocol method(s) - so handling what happens when user types into the search bar
self.searchController.searchResultsUpdater = self;
//this ViewController will be responsisble for implementing UISearchBarDelegate protocol methods(s)
self.searchController.searchBar.delegate = self;
}
- (void)styleTableView {
[[self tableView] setSectionIndexColor:[UIColor colorWithRed:100.0f/255.0f green:100.0f/255.0f blue:100.0f/255.0f alpha:1.0f]];
[[self tableView] setSectionIndexBackgroundColor:[UIColor colorWithRed:230.0f/255.0f green:230.0f/255.0f blue:230.0f/255.0f alpha:1.0f]];
}
#pragma mark - UITableViewDataSource methods
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [self.tableSections count];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSDictionary *sectionItems = [self.tableSectionsAndItems objectAtIndex:section];
NSArray *namesForSection = [sectionItems objectForKey:[self.tableSections objectAtIndex:section]];
return [namesForSection count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
return [self.tableSections objectAtIndex:section];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellReuseId = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellReuseId];
if(cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellReuseId];
}
NSDictionary *sectionItems = [self.tableSectionsAndItems objectAtIndex:indexPath.section];
NSArray *namesForSection = [sectionItems objectForKey:[self.tableSections objectAtIndex:indexPath.section]];
cell.textLabel.text = [namesForSection objectAtIndex:indexPath.row];
//show accessory disclosure indicators on cells only when user has typed into the search box
if(self.searchController.searchBar.text.length > 0) {
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
return cell;
}
#pragma mark - UITableViewDelegate methods
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
NSDictionary *sectionItems = [self.tableSectionsAndItems objectAtIndex:indexPath.section];
NSArray *namesForSection = [sectionItems objectForKey:[self.tableSections objectAtIndex:indexPath.section]];
NSString *selectedItem = [namesForSection objectAtIndex:indexPath.row];
//Log
NSLog(#"User selected %#", selectedItem);
}
//#pragma Segue
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([[segue identifier] isEqualToString:#"showDetail"]) {
NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
employee *employee = self.employees[indexPath.row];
EmployeeDetailViewController *employeeDetailViewController = segue.destinationViewController;
employeeDetailViewController.detailItem = employee;
}
}
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {
//only show section index titles if there is no text in the search bar
if(!(self.searchController.searchBar.text.length > 0)) {
NSArray *indexTitles = self.tableSections;
//HERE
//*indexTitles = [Item fetchDistinctItemGroupsInManagedObjectContext:self.managedObjectContext];
return indexTitles;
} else {
return nil;
}
}
- (void)tableView:(UITableView *)tableView willDisplayHeaderView:(UIView *)view forSection:(NSInteger)section
{
view.tintColor = [UIColor colorWithRed:100.0f/255.0f green:100.0f/255.0f blue:100.0f/255.0f alpha:1.0f];
UITableViewHeaderFooterView *header = (UITableViewHeaderFooterView *)view;
[header.textLabel setTextColor:[UIColor whiteColor]];
}
#pragma mark - UISearchResultsUpdating
-(void)updateSearchResultsForSearchController:(UISearchController *)searchController {
//get search text from user input
NSString *searchText = [self.searchController.searchBar text];
//exit if there is no search text (i.e. user tapped on the search bar and did not enter text yet)
if(!([searchText length] > 0)) {
return;
}
//handle when there is search text entered by the user
else {
//based on the user's search, we will update the contents of the tableSections and tableSectionsAndItems properties
[self.tableSections removeAllObjects];
[self.tableSectionsAndItems removeAllObjects];
NSString *firstSearchCharacter = [searchText substringToIndex:1];
//handle when user taps into search bear and there is no text entered yet
if([searchText length] == 0) {
//self.tableSections = [[Item fetchDistinctItemGroupsInManagedObjectContext:self.managedObjectContext] mutableCopy];
//self.tableSectionsAndItems = [[Item fetchItemNamesByGroupInManagedObjectContext:self.managedObjectContext] mutableCopy];
}
//handle when user types in one or more characters in the search bar
else if(searchText.length > 0) {
//the table section will always be based off of the first letter of the group
NSString *upperCaseFirstSearchCharacter = [firstSearchCharacter uppercaseString];
self.tableSections = [[[NSArray alloc] initWithObjects:upperCaseFirstSearchCharacter, nil] mutableCopy];
//there will only be one section (based on the first letter of the search text) - but the property requires an array for cases when there are multiple sections
//NSDictionary *namesByGroup = [Item fetchItemNamesByGroupFilteredBySearchText:searchText ////inManagedObjectContext:self.managedObjectContext];
//self.tableSectionsAndItems = [[[NSArray alloc] initWithObjects:namesByGroup, nil] mutableCopy];
}
//now that the tableSections and tableSectionsAndItems properties are updated, reload the UISearchController's tableview
[((UITableViewController *)self.searchController.searchResultsController).tableView reloadData];
}
}
#pragma mark - UISearchBarDelegate methods
- (void)searchBarCancelButtonClicked:(UISearchBar *)searchBar {
[self.tableSections removeAllObjects];
[self.tableSectionsAndItems removeAllObjects];
//self.tableSections = [[Item fetchDistinctItemGroupsInManagedObjectContext:self.managedObjectContext] mutableCopy];
//self.tableSectionsAndItems = [[Item fetchItemNamesByGroupInManagedObjectContext:self.managedObjectContext] mutableCopy];
}
#end

Answer 1

The problem is that, your are removing all objects at this line
[self.tableSectionsAndItems removeAllObjects];
and you have commented the lines, which again feels that array, just above the lines which you mentioned in your question. so, uncomment the following lines
//NSDictionary *namesByGroup = [Item fetchItemNamesByGroupFilteredBySearchText:searchText ////inManagedObjectContext:self.managedObjectContext];
//self.tableSectionsAndItems = [[[NSArray alloc] initWithObjects:namesByGroup, nil] mutableCopy];
And in numberOfRows Method, you are accessing the object at index on empty array that leads to crash.
[self.tableSectionsAndItems objectAtIndex:section];
So, uncomment those two lines above, in the following method and it will fix.
-(void)updateSearchResultsForSearchController:(UISearchController *)searchController
Try and share your results.