UITableVIew with Single Selection iOS - ios

Question

I am totally new to iOS development and have been requested by my company to jump into some code written by another amateur that left us and fix it. The main view of this app is just a table view and we would like the user to be able to select one cell from the table, which would highlight it and set some other buttons on the page to do something to that particular cell.
Making the other buttons on the page works just fine, as long as I know what cell is selected, so I am not too worried about that. But the code this other guy wrote to select one cell at a time is atrocious, and the code I tried to replace his with was better, but still very buggy.
My code is this written below (sort of adopted from the old stuff that I don't completely understand). The issue with it is that the background turns black when the cell is clicked twice in a row or if you change views and come back to this table view.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
for (int i = 0; i < [tableView numberOfRowsInSection:0]; i++) {
[tableView deselectRowAtIndexPath:currentSelection animated:true];
}
if(currentSelection.item == indexPath.item){
[tableView deselectRowAtIndexPath:currentSelection animated:true];
}
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
//highlight bg to light grey
cell.backgroundColor =[UIColor colorWithRed:200/255 green:200/255 blue:200/255 alpha:1.0f];
currentSelection = indexPath;
//code for other button functions
}
- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
//set bg back to white
cell.backgroundColor =[UIColor colorWithRed:255/255 green:255/255 blue:255/255 alpha:1.0f];
noSelectedRows = true;
}
If that is too terrible too look at and try to fix, I was looking at a tutorial provided by Apple that I wanted to understand a little better anyway. The following code was found here: https://developer.apple.com/library/ios/documentation/userexperience/conceptual/tableview_iphone/ManageSelections/ManageSelections.html
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[tableView deselectRowAtIndexPath:indexPath animated:NO];
NSInteger catIndex = [taskCategories indexOfObject:self.currentCategory];
if (catIndex == indexPath.row) {
return;
}
NSIndexPath *oldIndexPath = [NSIndexPath indexPathForRow:catIndex inSection:0];
UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];
if (newCell.accessoryType == UITableViewCellAccessoryNone) {
newCell.accessoryType = UITableViewCellAccessoryCheckmark;
self.currentCategory = [taskCategories objectAtIndex:indexPath.row];
}
UITableViewCell *oldCell = [tableView cellForRowAtIndexPath:oldIndexPath];
if (oldCell.accessoryType == UITableViewCellAccessoryCheckmark) {
oldCell.accessoryType = UITableViewCellAccessoryNone;
}
}
The only things I need to know about that last code is where variables like self.currentCategory and taskCategories are coming from. As of now, there don't seem to be any similar variables in the code I am working with, so I would like to know what I have to point to or create.
This is also my first post on StackOverflow, so if I left out something important, please let me know.

Answer 1

The UITableView is a huge control, and it can be implemented in several ways. By your description, I think you using it with Static Grouped cells, in order to compose a form, right?
Actually selection display is handled automatically by the UITableView, so the code for didDeselecteRowAtIndex path which manually change cells background may be one source if the buggy behavior. Notice in the Apple Sample that they are using a similar logic to change the accessory view when cells are tapped, which need to be set manually.
If you're using the Storyboard and Template cells, you can set the "Selection" property on the cell to change the color when it is selected. Then you can remove the logic for changing cells backgrounds. I think it could be a good starting point....

Answer 2

You can right click on the variable and select Jump To Definition and it will show you where its declared.
As far as the rest of the code, what the other answers said is correct.
I suggest picking up a book on iOS development as well. Big Nerd Ranch's book is a great start.

Answer 3

One of your problems is, that
200/255 is 0
use 200/255.0f instead

Answer 4

Complementing Justin answers, here are some links. The iOS Apprentice Bundle is a great jumpstart material, that guides you through the creation of several Apps, pinpoint basics of iOS, such as the table view. I highly recommend!
http://www.raywenderlich.com/store/ios-apprentice
This series of videos also has a great introduction to Table Views, it will take less than a hour and will show the big picture on using UITableViews, this one is free:
https://www.youtube.com/watch?v=Rh-vfLXsTac