Dynamic UITableView with multiple custom UITableViewCells - objective-c

Question

I've been working on this for a while, doing a lot of research, but haven't found a solution I was particularly happy with.
Here's the situation:
The tableview is a settings page of sorts, with dynamic content. For example, rows need to be added and removed when a switch changes state in one of the cells. To accomplish this, I chose the delegate pattern to notify of the cell's changes
The problem:
1) I'm not sure what object should be the proper "owner," and therefore delegate, of the custom cells. It seems to me that the uitableview should delegate for the cells, and in turn it delegates to the view controller.
2) Whichever object delegates for the custom cells, it has to "figure out" which property would need to be updated based on the call. This is a problem because of multiple cells of the same type being applied to different properties.
For example, say there are 2 sections, each with 1 switch cell. When one of the cells fires its delegate call to notify of the change in state, the view controller has to determine which part of the model to update. In this example, you could easily check which section the cell was in to update the model, however it wouldn't really solve the problem, because if you were to add a second switch cell to one of the sections in the future, it would break.
Note:
As you'll see in the code below, it is conceivable to utilize the indexPath to check the property being edited. However, it would result in either a ever growing if/elseif or switch statement checking which property corresponds to which indexPath.
Reason being: at least some properties are not pointers, so storing them in an array and editing them directly wouldn't affect the data, and would eventually need to be translated using literals to the actual data object.
Here's some of what I have to better illustrate:
#protocol CustomUITextFieldCellDelegate <NSObject>
- (void)cellDidBeginEditingTextField:(CustomUITextFieldCell *)cell;
- (void)cellDidEndEditingTextField:(CustomUITextFieldCell *)cell;
#end
#interface CustomUITextFieldCell : UITableViewCell <UITextFieldDelegate>
#property (nonatomic, strong) NSString *title;
#property (nonatomic, assign) id <CustomUITextFieldCellDelegate> delegate;
#end
'
#protocol CustomTableViewDelegate <UITableViewDelegate>
- (void)textFieldCell:(CustomUITextFieldCell *)cell didBeginEditingIndexPath:(NSIndexPath *)indexPath;
- (void)textFieldCell:(CustomUITextFieldCell *)cell didEndEditingIndexPath:(NSIndexPath *)indexPath;
#end
#interface CustomTableView : UITableView <CustomUITextFieldCellDelegate>
#property (nonatomic, assign) id <CustomTableViewDelegate> delegate;
#end
In the ViewController, delegate for the CustomUITableView:
- (void)textFieldCell:(TTD_UITextFieldCell *)cell didBeginEditingIndexPath:(NSIndexPath *)indexPath {
// determine which property is being edited
// update model
}
Thanks for any help in advance! I'm curious to see how you would tackle this problem.

Answer 1

If you know which property the value is editing when creating the cell, you can use blocks instead of the delegate pattern, like this:
// for text editing
typedef void (^TextCellSetValueBlock)(NSString *);
typedef NSString *(^TextCellGetValueBlock)();
#interface CustomUITextFieldCell: UITableViewCell {
// ...
#property (nonatomic, copy) TextCellSetValueBlock onSetValue;
#property (nonatomic, copy) TextCellGetValueBlock onGetValue;
// ...
}
When creating the cell, assign onSetValue/onGetValue to blocks that read/write the appropriate property from your model, and call onGetValue()/onSetValue() from your cell when you want to get/set the property.
For the boolean switch that turns on/off parts of your UI, you can have your onSetValue blocks update your model and also add/remove cells as a side effect.