Lighter View Controllers

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Lighter View Controllers Chris Eidhof NSSpain 2013 Wednesday, September 18, 13

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What’s the largest ﬁle in your project? Wednesday, September 18, 13

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What’s the largest ﬁle in your project? 0 200 400 600 800 Wednesday, September 18, 13

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(image by Manu Cornet) Wednesday, September 18, 13

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(image by Manu Cornet) Wednesday, September 18, 13

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View controllers are the non-reusable part of your project Wednesday, September 18, 13

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find . -name "*.m" -exec wc -l "{}" \; | sort -n Wednesday, September 18, 13

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154 ./ViewControllers/THUserPrioritiesViewController.m 154 ./ViewControllers/THZoomingNavigationController.m 155 ./Extensions/NSArray+Extensions.m 155 ./Extensions/UIView+Extensions.m 168 ./Controllers/THPriorityTimelineCollectionController.m 179 ./Controllers/THUserScreenInstancesController.m 183 ./ViewControllers/THRootViewController.m 183 ./ViewControllers/THScreenInstanceViewController.m 185 ./Model/User+Extensions.m 192 ./ViewControllers/THEditPriorityViewController.m 221 ./ViewControllers/THScreeningBarViewController.m 243 ./Views/THTimeLineView.m 263 ./ViewControllers/THCardsViewController.m 279 ./Views/THSkillboxView.m 325 ./THStyleSheet.m Wednesday, September 18, 13

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... but this view controller is important! Wednesday, September 18, 13

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Steps Project: A complete OS in <20K lines Wednesday, September 18, 13

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What can we do? Wednesday, September 18, 13

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A view controller intermediates between model and view Wednesday, September 18, 13

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Model logic Wednesday, September 18, 13

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View Logic Wednesday, September 18, 13

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View Layout Wednesday, September 18, 13

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Webservice Wednesday, September 18, 13

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View Controller View Child View Controller Model Webservice Wednesday, September 18, 13

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Demo Wednesday, September 18, 13

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View Controller View Child View Controller Model Webservice Wednesday, September 18, 13

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View Controller View Child View Controller Model Webservice Wednesday, September 18, 13

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Model Logic Move into model subclass or into a separate class Wednesday, September 18, 13

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Some Stats 18 ./NestedTodoList/main.m 30 ./Item.m 31 ./NestedTodoList/Store.m 49 ./NestedTodoList/PersistentStack.m 52 ./NestedTodoList/AppDelegate.m 255 ./NestedTodoList/ItemViewController.m Wednesday, September 18, 13

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What does it do? ‣ View Setup ‣ Table View Delegate ‣ Table View Datasource ‣ Fetched Results Controller Delegate ‣ Adding items ‣ Deleting Items ‣ ... Wednesday, September 18, 13

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Custom Datasource What does it do? ‣ View Setup ‣ Table View Delegate ‣ Table View Datasource ‣ Fetched Results Controller Delegate ‣ Adding items ‣ Deleting Items ‣ ... Wednesday, September 18, 13

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Custom Datasource Model What does it do? ‣ View Setup ‣ Table View Delegate ‣ Table View Datasource ‣ Fetched Results Controller Delegate ‣ Adding items ‣ Deleting Items ‣ ... Wednesday, September 18, 13

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Model - (BOOL)textFieldShouldReturn:(UITextField*)t { NSString* title = t.text; NSUInteger order = self.parent.children.count; Item* item = [NSEntityDescription insertNewObjectForEntityForName:@"Item" inManagedObjectContext:self.moc]; item.title = title; item.parent = self.parent; item.order = @(order); ... } Wednesday, September 18, 13

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Model - (BOOL)textFieldShouldReturn:(UITextField*)t { NSString* title = t.text; [Item insertItemWithTitle:title parent:self.parent inManagedObjectContext:self.moc]; ... } Wednesday, September 18, 13

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- (void)deleteItem:(id)object { Item* item = object; NSSet* siblings = item.parent.children; NSPredicate* predicate = [NSPredicate pre NSSet* itemsAfterSelf = [siblings filtere [itemsAfterSelf enumerateObjectsUsingBloc { sibling.order = @(sibling.order.integ }]; [item.moc deleteObject:item]; } Wednesday, September 18, 13

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- (void)prepareForDeletion { NSSet* siblings = self.parent.children; NSPredicate* p = [NSPredicate predicateWithFormat:@"order > %@", self.order]; NSSet* itemsAfterSelf = [siblings filteredSetUsingPredicate:p]; [itemsAfterSelf enumerateObjectsUsingBlock: ^(Item* sibling, BOOL* stop) { sibling.order = @(sibling.order.integerValue - 1); }]; } Wednesday, September 18, 13

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Some Stats 18 ./NestedTodoList/main.m 31 ./NestedTodoList/Store.m 49 ./NestedTodoList/PersistentStack.m 52 ./NestedTodoList/AppDelegate.m 54 ./Item.m 241 ./NestedTodoList/ItemViewController.m Wednesday, September 18, 13

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View Controller View Child View Controller Model Webservice UITableViewDS Wednesday, September 18, 13

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View Controller View Child View Controller Model Webservice UITableViewDS Wednesday, September 18, 13

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@interface FetchedResultsControllerDataSource : NSObject Wednesday, September 18, 13

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#pragma mark UITableViewDatasource Wednesday, September 18, 13

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- (NSInteger)numberOfSectionsInTableView:(UITableView*)t { return self.fetchedResultsController.sections.count; } Wednesday, September 18, 13

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- (NSInteger)tableView:(UITableView*)t numberOfRowsInSection:(NSInteger)s { id section = self.fetchedResultsController.sections[s]; return section.numberOfObjects; } Wednesday, September 18, 13

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- (UITableViewCell*)tableView:(UITableView*)t cellForRowAtIndexPath:(NSIndexPath*)ip Wednesday, September 18, 13

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#pragma mark NSFetchedResultsControllerDelegate Wednesday, September 18, 13

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- (void)controller:(NSFetchedResultsController*)c didChangeObject:(id)anObject atIndexPath:(NSIndexPath*)indexPath forChangeType:(NSFetchedResultsChangeType)ct newIndexPath:(NSIndexPath*)newIndexPath Wednesday, September 18, 13

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@property (nonatomic, weak) id delegate; Wednesday, September 18, 13

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- (UITableViewCell*)tableView:(UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath { id object = [self.frc objectAtIndexPath:indexPath]; id cell = [tableView dequeueReusableCellWithIdentifier:self.reuseIdentifier forIndexPath:indexPath]; [self.delegate configureCell:cell withObject:object]; return cell; } Wednesday, September 18, 13

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Some Stats (3) 25 ./NestedTodoList/Store.m 49 ./NestedTodoList/PersistentStack.m 52 ./NestedTodoList/AppDelegate.m 64 ./Item.m 111 ./NestedTodoList/FRCDataSource.m 162 ./NestedTodoList/ItemViewController.m Wednesday, September 18, 13

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Code re-use ☺ Wednesday, September 18, 13

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Other Candidates UICollectionViewDataSource UIPageViewControllerDataSource UIPickerViewDataSource Wednesday, September 18, 13

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More candidates UICollectionViewDelegate UIScrollViewDelegate UITableViewDelegate UITableViewDelegate UITextFieldDelegate Wednesday, September 18, 13

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... or use a super class? Wednesday, September 18, 13

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Superclass disadvantages You only have 1 superclass Harder to switch from table view to collection view Easier to make mistakes: e.g. forget to call super methods. Wednesday, September 18, 13

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Superclass disadvantages You only have 1 superclass Harder to switch from table view to collection view Easier to make mistakes: e.g. forget to call super methods. Wednesday, September 18, 13

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Superclass disadvantages You only have 1 superclass Harder to switch from table view to collection view Easier to make mistakes: e.g. forget to call super methods. objc_requires_super Wednesday, September 18, 13

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View Controller View Child View Controller Model Webservice Wednesday, September 18, 13

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View Controller View Child View Controller Model Webservice Wednesday, September 18, 13

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- (UITableViewCell*)tableView:(UITableView*)t cellForRowAtIndexPath:(NSIndexPath*)ip Wednesday, September 18, 13

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// PhotoCell+ConfigureForPhoto.h @interface PhotoCell (ConfigureForPhoto) - (void)configureForPhoto:(Photo *)photo; @end Wednesday, September 18, 13

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UITableViewController ‣ Clears selection ‣ Reloads data ‣ Flashes scroll indicators ‣ Editing ‣ Auto-scrolls to ﬁrst responder ‣ Refresh control ‣ .... Wednesday, September 18, 13

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View Controller Containment Wednesday, September 18, 13

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... or in code [self addChildViewController:sliderController]; [self.view addSubview:sliderController]; [UIView animateWithDuration:0.25 animations:^{ sliderController.view.alpha = 1; [sliderController didMoveToParentViewController:self]; }]; Wednesday, September 18, 13

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Communication Wednesday, September 18, 13

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Delegate Blocks KVO Wednesday, September 18, 13

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Too much overhead? Wednesday, September 18, 13

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Interface Builder Wednesday, September 18, 13

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@interface MyCell : UITableViewCell @property (weak) IBOutlet UISlider *slider; @property (weak) IBOutlet UISwitch *switch; @end Wednesday, September 18, 13

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Custom objects in your nib Wednesday, September 18, 13

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Outlets also work Wednesday, September 18, 13

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@interface NSObject(UINibLoadingAdditions) - (void)awakeFromNib; @end Wednesday, September 18, 13

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Testing Wednesday, September 18, 13

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Testing Wednesday, September 18, 13

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Testing Wednesday, September 18, 13

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Separate data source is easy to test Wednesday, September 18, 13

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Category on cell is easy to test Wednesday, September 18, 13

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View Controllers are hard to test Wednesday, September 18, 13

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- (void)testNibLoading; { id mockNavController = [self autoVerifiedMockForClass: [UINavigationController class]]; PhotosViewController *photosViewController = [[PhotosViewController alloc] init]; id photosViewControllerMock = [self autoVerifiedPartialMockForObject: photosViewController]; [[[photosViewControllerMock stub] andReturn:mockNavController] navigationController]; Wednesday, September 18, 13

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Tools Sort ﬁles by length Know your libraries Refactor: Use XCode 5 AppCode Wednesday, September 18, 13

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Tools Pull out data sources Use View Controller Containment Move code to models and views Wednesday, September 18, 13

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About Me @chriseidhof http://www.objc.io http://www.uikonf.com http://chris.eidhof.nl Wednesday, September 18, 13