Super brief talk I gave about the various approaches for configuring a UITableViewCell with a model object. I gave this talk at the March Cocoaheads meeting in 2013. More information about the meeting below. http://www.brynbodayle.com/nashville-cocoaheads-recap-321/

1. UITableViewCell + Model Object
Bryn Bodayle
iOS Developer

2. Three Ways?

3. 1. View controller configuring
2. Pass model to cell
3. Categories

4. 1. View controller configuring
- “Default” method
- Maintains strict MVC
- Bad reuse: copy & paste
- Easy but cluttered
- Dynamic cell heights clunky
- Goodbye skinny view controllers
- Lots of constants

5. 1. View controller configuring
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *reuseIdentifier = @"Tweet Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reuseIdentifier];
if (nil == cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:reuseIdentifier];
cell.textLabel.font = [UIFont systemFontOfSize:14];
cell.textLabel.numberOfLines = 0;
cell.textLabel.backgroundColor = [UIColor clearColor];
cell.contentView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"listbg.png"]];
}
cell.textLabel.text = [[_statuses objectAtIndex:indexPath.row] text];
return cell;
}

6. 1. View controller configuring
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
! static NSString *CellIdentifier = @"CustomTableViewCell";
! CustomTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
! if (cell == nil)
! ! cell = [[CustomTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
ModelObject *object = self.data[indexPath.section][indexPath.row];
NSMutableAttributedString *attributedTitle = [[NSMutableAttributedString alloc] initWithString:object.title];
[attributedTitle setAttributes:@{UITextAttributeFont : [UIFont fontWithName:@"Comic Sans" size:20]} range:NSMakeRange(0, 10)];
[attributedTitle setAttributes:@{UITextAttributeFont : [UIFont fontWithName:@"Zapfino" size:20]} range:NSMakeRange(10, 20)];
[cell.titleText setAttributedText:attributedTitle];
[cell.titleText sizeToFit];
cell.detailText.text = object.detail;
[cell.titleText sizeToFit];
cell.profileImage.image = object.image;
[UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^(void) {
cell.profileImage.alpha = 1;
} completion:^(BOOL finished) {
}];
! return cell;
}

7. 1. View controller configuring
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
ModelObject *object = self.data[indexPath.section][indexPath.row];
if(object.image) {
CGSize size = [object.detail sizeWithFont:DETAIL_FONT constrainedToSize:CGSizeMake(DETAIL_WIDTH, MAXFLOAT)
lineBreakMode:DETAIL_LINE_BREAK_MODE];
return MAX(size.height + CELL_PADDING, 70);
}
else {
CGSize size = [object.detail sizeWithFont:DETAIL_FONT_SMALL constrainedToSize:CGSizeMake(DETAIL_WIDTH_IMAGE,
MAXFLOAT) lineBreakMode:DETAIL_LINE_BREAK_MODE];
return MAX(size.height + CELL_PADDING, 50);
}
}

8. 2. Pass model to cell
- Quick & easy
- Easy dynamic heights
- Tightly couples cell to model object
- Clean interface
- Nimbus Framework
- Deadly sin?

9. When a UITableViewCell subclass accepts a model object parameter and
updates its constituent subviews as I have described, it is behaving as a data
transformer, not a controller. It does not care about any future updates to the
model unless the controller tells it to transform the updated model object, or
to transform a completely different model instance.
- Paul Goracke

10. 2. Pass model to cell
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
! static NSString *CellIdentifier = @"CustomTableViewCell";
! CustomTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
! if (cell == nil)
! ! cell = [[CustomTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier];
!
ModelObject *object = self.data[indexPath.section][indexPath.row];
[cell updateCellWithObject:object];
! return cell;
}

11. 2. Pass model to cell
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
ModelObject *object = self.data[indexPath.section][indexPath.row];
return [CustomTableViewCell cellHeightForDetailText:object.detail];
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
ModelObject *object = self.data[indexPath.section][indexPath.row];
return [CustomTableViewCell cellHeightForObject:object];
}

12. 3. Categories
- Middle ground
- Loose coupling
- Extra files
- Subviews must be public
- Multiple model objects for one cell

13. 3. Categories
#import "FAScoreboardCell.h"
@class Athlete;
@interface FAScoreboardCell (Athlete)
+ (NSInteger)heightForText:(NSString *)text;
- (void)updateWithAthlete:(Athlete *)athlete;
@end

14. Further Reading
-Brent Simmons: “UITableViewCell Is Not a Controller”
- http://inessential.com/2012/12/31/uitableviewcell_is_not_a_controller
-Paul Goracke: “UITableViewCell Is Not a Controller, But...”
- http://corporationunknown.com/blog/2013/01/01/uitableviewcell-is-not-a-
controller-but/
-Sebastian Rehnby: “Skinnier Controllers Using View Categories”
- http://www.sebastianrehnby.com/blog/2013/01/01/skinnier-controllers-
using-view-categories/

15. Questions?