UITableViewCell + Model Object

Bryn BodayleiOS Developer

Three Ways?

1. View controller con!guring

2. Pass model to cell

3. Categories

-“Default” method

-Maintains strict MVC

-Bad reuse: copy & paste

-Easy but cluttered

-Dynamic cell heights clunky

-Goodbye skinny view controllers

-Lots of constants

1. View controller con!guring

- (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;}

1. View controller con!guring

- (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;}

1. View controller con!guring

-(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);

}}

1. View controller con!guring

-Quick & easy

-Easy dynamic heights

-Tightly couples cell to model object

-Clean interface

-Nimbus Framework

-Deadly sin?

2. Pass model to cell

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

- (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;}

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];

2. Pass model to cell

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { ModelObject *object = self.data[indexPath.section][indexPath.row]; return [CustomTableViewCell cellHeightForObject:object];}

-Middle ground

-Loose coupling

-Extra !les

-Subviews must be public

-Multiple model objects for one cell

3. Categories

#import "FAScoreboardCell.h"

@class Athlete;

@interface FAScoreboardCell (Athlete)

+ (NSInteger)heightForText:(NSString *)text;- (void)updateWithAthlete:(Athlete *)athlete;

@end

3. Categories

-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/

Further Reading

Questions?