Scroll down uitableview to specific date - iphone

Question

I would like to know if I have a uitable, the title of each table items is a date and time. May I know how to code if I want the table auto scroll down to a cell with specific date e.g. Today's date? What should I code in the viewDidLoad method?
Here is my code for the table,
#interface PictureListMainTable : UITableViewController{
IBOutlet UIButton*scroll;
}
#property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (strong, nonatomic) NSMutableArray *pictureListData;
#property (strong, nonatomic) IBOutlet UIButton*scroll;
- (void)readDataForTable;
-(IBAction)scrolldown:(id)sender;
#end
#synthesize managedObjectContext, pictureListData;
#synthesize scroll;
// When the view reappears, read new data for table
- (void)viewWillAppear:(BOOL)animated
{
// Repopulate the array with new table data
[self readDataForTable];
}
// Grab data for table - this will be used whenever the list appears or reappears after an add/edit
- (void)readDataForTable
{
// Grab the data
pictureListData = [CoreDataHelper getObjectsForEntity:#"Pictures" withSortKey:#"title" andSortAscending:YES andContext:managedObjectContext];
// Force table refresh
[self.tableView reloadData];
}
#pragma mark - Actions
// Button to log out of app (dismiss the modal view!)
- (IBAction)logoutButtonPressed:(id)sender
{
[self dismissModalViewControllerAnimated:YES];
}
#pragma mark - Segue methods
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Get a reference to our detail view
PictureListDetail *pld = (PictureListDetail *)[segue destinationViewController];
// Pass the managed object context to the destination view controller
pld.managedObjectContext = managedObjectContext;
// If we are editing a picture we need to pass some stuff, so check the segue title first
if ([[segue identifier] isEqualToString:#"EditPicture"])
{
// Get the row we selected to view
NSInteger selectedIndex = [[self.tableView indexPathForSelectedRow] row];
// Pass the picture object from the table that we want to view
pld.currentPicture = [pictureListData objectAtIndex:selectedIndex];
}
}
#pragma mark - Table view data source
// Return the number of sections in the table
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
// Return the number of rows in the section (the amount of items in our array)
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [pictureListData count];
}
// Create / reuse a table cell and configure it for display
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
// Get the core data object we need to use to populate this table cell
Pictures *currentCell = [pictureListData objectAtIndex:indexPath.row];
// Fill in the cell contents
cell.textLabel.text = [currentCell title];
cell.detailTextLabel.text = [currentCell desc];
// If a picture exists then use it
if ([currentCell smallPicture])
{
cell.imageView.contentMode = UIViewContentModeScaleAspectFit;
cell.imageView.image = [UIImage imageWithData:[currentCell smallPicture]];
}
return cell;
}
// Swipe to delete has been used. Remove the table item
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete)
{
// Get a reference to the table item in our data array
Pictures *itemToDelete = [self.pictureListData objectAtIndex:indexPath.row];
// Delete the item in Core Data
[self.managedObjectContext deleteObject:itemToDelete];
// Remove the item from our array
[pictureListData removeObjectAtIndex:indexPath.row];
// Commit the deletion in core data
NSError *error;
if (![self.managedObjectContext save:&error])
NSLog(#"Failed to delete picture item with error: %#", [error domain]);
// Delete the row from the data source
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
}
#end
Thanks

Answer 1

Since you are dealing with dates, it's better to create an array of dates and find current date using dateComponents.
In this snippet dates is an array of NSDate instances.
NSCalendar *cal = [NSCalendar currentCalendar];
NSDate *today = [NSDate date];
[self.dates enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSDate *date = (NSDate *)obj;
NSDateComponents *components = [cal components:NSDayCalendarUnit
fromDate:date
toDate:today
options:0];
if ([components day]==0) {
*stop = TRUE;
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:idx inSection:0];
[self.tableView scrollToRowAtIndexPath:indexPath
atScrollPosition:UITableViewScrollPositionTop
animated:YES];
}
}];
EDIT :
- (void)viewWillAppear:(BOOL)animated
{
// Repopulate the array with new table data
[self readDataForTable];
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:#"dd.MMMM - EEEE"];
NSDate *today = [NSDate date];
[pictureListData enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
Pictures *picture = (Pictures *)obj;
NSDate *date = [dateFormatter dateFromString:picture.title];
NSDateComponents *components = [cal components:NSDayCalendarUnit
fromDate:date
toDate:today
options:0];
if ([components day]==0) {
*stop = TRUE;
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:idx inSection:0];
[self.tableView scrollToRowAtIndexPath:indexPath
atScrollPosition:UITableViewScrollPositionTop
animated:YES];
}
}];
}

Answer 2

Firstly find index of todays date or any other date in UITableView's dataSource like this:
I assume date format of search date and data source date are same
NSInteger index = NSNotFound;
if ([tableViewArray containsObject:dateHere]) {
index = [tableViewArray indexOfObject:dateHere];
}
Now scroll using scrollToRowAtIndexPath
[yourTableView scrollToRowAtIndexPath:NSIndexPath indexPathForRow:index inSection:0] atScrollPosition:UITableViewScrollPositionNone animated:YES];
EDIT : Use these ScrollPosition to your requirement
UITableViewScrollPositionNone,
UITableViewScrollPositionTop,
UITableViewScrollPositionMiddle,
UITableViewScrollPositionBottom

Answer 3

You have to calculate indexpath for specific date. And use this delegate to scroll down or scroll Up the UITableViewCells in TableView
[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionNone animated:NO];
if you know positions of UITableViewCells to use
[tableView setContentOffset:CGPointMake(0,0) animated:YES];