How to uncheck all rows using UITableViewCellAccessoryCheckmark - iphone

Question

I've got a UITableView with each row containing a checkbox using UITableViewCellAccessoryCheckmark. I can't figure out how to uncheck all the checkboxes using the didSelectRowAtIndexPath method.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *oldCell;
int count = [self.myTableRowNamesArray count];
for (NSUInteger i = 0; i < count; ++i) {
// Uncheck all checkboxes
// OF COURSE THIS DOESN'T WORK
// BECAUSE i IS AN INTEGER AND INDEXPATH IS A POINTER
FOO: oldCell = [myTableView cellForRowAtIndexPath:(int)i];
// GOOD CODE:
oldCell = [penanceOptionsTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:0]];
oldCell.accessoryType = UITableViewCellAccessoryNone;
}
UITableViewCell *newCell = [myTableView cellForRowAtIndexPath:indexPath];
newCell.accessoryType = UITableViewCellAccessoryCheckmark;
}

Answer 1

Instead of modifying the .accessoryType of all cells in didSelectRowAtIndexPath:, I suggest storing the selected index in some ivar, and change the .accessoryType in the data source's -tableView:cellForRowAtIndexPath: method, i.e.
-(void)tableView:(UITableView*)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath {
self.selectedIndexPath = indexPath;
[tableView reloadData];
}
-(UITableViewCell*)tableView:(UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath {
...
cell.accessoryType = [indexPath compare:self.selectedIndexPath] == NSOrderedSame
? UITableViewCellAccessoryCheckmark
: UITableViewCellAccessoryNone;
...
}
With this, only visible cells will be affected, and the million other cells outside of the screen won't need to be modified.
Quite right, here's a full implementation in Swift in the general case of selecting a cell .. you'd use selectedIndexPath elsewhere in the class as you see fit. For example, in cellForRowAtIndexPath to choose the appropriate cell prototype.
// SelectingTableViewController
import UIKit
class SelectingTableViewController: UITableViewController
{
internal var selectedIndexPath:NSIndexPath? = nil
override func viewDidLoad()
{
super.viewDidLoad()
tableView.estimatedRowHeight = 68.0
tableView.rowHeight = UITableViewAutomaticDimension
self.clearsSelectionOnViewWillAppear = false;
}
override func tableView
(tableView:UITableView, didSelectRowAtIndexPath indexPath:NSIndexPath)
{
print("did select....")
// in fact, was this very row selected,
// and the user is clicking to deselect it...
// if you don't want "click a selected row to deselect"
// then on't include this clause.
if selectedIndexPath == indexPath
{
print("(user clicked on selected to deselect)")
selectedIndexPath = nil
tableView.reloadRowsAtIndexPaths(
[indexPath],
withRowAnimation:UITableViewRowAnimation.None)
tableView.deselectRowAtIndexPath(indexPath, animated:false)
return
}
// in fact, was some other row selected??
// user is changing to this row? if so, also deselect that row
if selectedIndexPath != nil
{
let pleaseRedrawMe = selectedIndexPath!
// (note that it will be drawn un-selected
// since we're chaging the 'selectedIndexPath' global)
selectedIndexPath = indexPath
tableView.reloadRowsAtIndexPaths(
[pleaseRedrawMe, indexPath],
withRowAnimation:UITableViewRowAnimation.None)
return;
}
// no previous selection.
// simply select that new one the user just touched.
// note that you can not use Apple's willDeselectRowAtIndexPath
// functions ... because they are freaky
selectedIndexPath = indexPath
tableView.reloadRowsAtIndexPaths(
[indexPath],
withRowAnimation:UITableViewRowAnimation.None)
}
}

Answer 2

for (UITableViewCell *cell in [myTableView visibleCells]) {
cell.accessoryType = UITableViewCellAccessoryNone;
}
But really, you'd be better off just modifying the one cell that actually has the checkmark set. You have to have stored this information somewhere in your model anyway.

Answer 3

You're probably setting some kind of property with this method.
So what i do is:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// 1. first unsetting the property
[object someProperty:nil];
// 2. call the reloadData method to uncheck all the checkmarks
[tableView reloadData];
// 3. check the selected cell
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
[cell setAccessoryType:UITableViewCellAccessoryCheckmark];
// 4. set the checked property
[object setSomeProperty:[indexpath row]];
}
And in my cellForRowAtIndexPath methods i got something like the following code:
if([object someProperty] == [indexpath row]){
[cell setAccessoryType:UITableViewCellAccessoryCheckmark];
} else {
[cell setAccessoryType:UITableViewCellAccessoryNone];
}

Answer 4

Yes, cellForRowAtIndexPath: uses NSIndexPath instead of integer so make indexpath by using
indexPathForRow:inSection:
if you are using one section then your loop is fine just pass i in row and 0 for section.