UITableViewCell changing UITableView's datasource - ios

Question

This will be really useful for me since I have been struggling with this issue for some time. Every time I am trying to create a custom UITableViewCell and use it in a UITableView, things get mixed up. I believe it is because of the function I use to fill the cell with, in this example it's name is fillPlayerCellWithPlayer:.
I have a NSArray of PlayerContacts as my DataSource of the UITableView. My idea is to fill the cell's contents like UILabels and UIImageViews and etc with each PlayerContact properties. The usual practice is to fill these properties right in cellForRowAtIndexPath like: tablecell.playerNameLabel.text = player.playerName and so on. But I implement it like as follows for convenience and reasons I will tell later down below:
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *cellIdentifier = #"PlayerCellID";
AddPlayerObjectCell *tablecell = (AddPlayerObjectCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
NSArray * chosenPlayerArray = [self generatePlayersArrayForCategoryRow:selectedCategoryIndexRow];
NSMutableDictionary * dict = (NSMutableDictionary *)[chosenPlayerArray objectAtIndex:indexPath.row];
PlayerContact * player = (PlayerContact *)[dict objectForKey:#"sgfPlayer"];
[tablecell fillPlayerCellWithPlayer:player];
return tablecell;}
To explain why I don't use the common practice method, first let me share the fillPlayerCellWithPlayer function:
- (void) fillPlayerCellWithPlayer : (PlayerContact *) player {
[self createGestureRegocnizer];
myPlayer = player; //this sets the player as the private variable of AddPlayerObjectCell class
cellItemLabel.text = myPlayer.playerName;
cellItemSubLabel.text = myPlayer.playerTeam;
UIImage * img = [UIImage imageNamed:#"messi.JPG"];
cellItemImageView.image = img; }
- (void) createGestureRegocnizer{
UITapGestureRecognizer *gesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTapFrom)];
gesture.delegate = self;
[self addGestureRecognizer:gesture];}
- (void) handleTapFrom{
NSString * imageName = #"unselected_user_icon.png";
NSString * imageNameSelected = #"selected_user_icon.png";
if(playerSelected){
playerSelected = NO;
myPlayer.playerSelected = playerSelected;
[cellItemSelectionImageView setImage:[UIImage imageNamed:imageName]];}
else{
playerSelected = YES;
myPlayer.playerSelected = playerSelected;
[cellItemSelectionImageView setImage:[UIImage imageNamed:imageNameSelected]];}}
As You can see, when the user touches the cell, handleTapFrom fires and i can change the playerSelected property of myPlayer so i can later on use this info to filter my main array for selected players.
One of my problems is that whenever i slide my finger in the tableview of players, their selected checkmarks gets changed like crazy. I guess this is caused by my using reusable cells logic in a wrong way. If you guys can suggest me a way to this properly, i would be really happy.
And my second question is more important for me since, if you guys say its true, I want to use it as a general logic throughout my app design. Lets say i passed a NSArray named playersArray to the tableview as datasource. And the cell class changed the playersArray object that corresponds to its indexPath. In my controller class, and the classes that can access playersArray, this change is observed. This is good news for me because i don't need to make a copy of array and change its contents accordingly. Do you friends think this is a good practice for a UITableViewCell to change the contents of its UITableView's DataSource? or is UITableViewCell's only job to display a cell as needed? Should I implement this some other way? like delegation or something if I want to update the datasource?
Thank you very much in advance. I can be more clear in anyway if you guys need me to.
Aytunç İşseven

Answer 1

In general you should avoid that the Cell is holding the data model itself and manipulating them. You also should avoid creating & adding this gesture recogniser multiple times (as that will happen if you call fillPlayerCellWithPlayer: and the cell is reused). That will increase the count of the tap recognisers and each of the will trigger the a tap. Instead you could override
- (void)setSelected:(BOOL)selected animated:(BOOL)animated
on the UITableViewCell and handle your selection there. This will be triggered each time you change the selection state of the UITableViewCell. You should only change the visual appearance of the cell here as the cell should not hold the player object.
To handle the selection of the player just implement the UITableViewDelegate method (on your controller)
- (NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath
and handle the manipulation of your data model there.
The reason why is:
The UITableViewCell is a view and following the Model-View-Controller Pattern (which Appkit is based on) the view should just represent the model without managing it. The controller (which implements the UITableViewDelegate - e.g. a UIViewController) is the connector between those two and should be the one managing the model information instead of the view as you suggested.