Cocoa Touch: The Good, The Bad and The Ugly

This is a talk I gave at Alt Tech Talks London, as a try out for MCE.

Transcript

2. Cocoa Touch The Good, The Bad and The Ugly Chris Eidhof
3. Cocoa Touch The Ugly, The Good and The Bad Chris Eidhof
4. commit c416c1d259bddaa74833e6df5acd770f85622293 Author: Chris Eidhof <ce@tupil.com> Date: Wed Jan 7 11:54:34 2009 +0100 Empty project
7. I thought I was a pretty good programmer
8. I knew PHP, Ruby and Haskell
9. How hard can it be?
11. The ugly
12. Example code @interface HiscoreTableViewCell : UITableViewCell { IBOutlet UIImageView *badge; IBOutlet UILabel *badgeTitle; IBOutlet UILabel *name1; IBOutlet UILabel *name2; IBOutlet UILabel *name3; IBOutlet UILabel *position1; IBOutlet UILabel *position2; IBOutlet UILabel *position3; IBOutlet UILabel *score1; IBOutlet UILabel *score2; IBOutlet UILabel *score3; }
13. Example code (continued) @property (nonatomic,readonly) UIImageView* badge; @property (nonatomic,readonly) UILabel *badgeTitle; @property (nonatomic,readonly) UILabel *name1; @property (nonatomic,readonly) UILabel *name2; @property (nonatomic,readonly) UILabel *name3; @property (nonatomic,readonly) UILabel *position1; @property (nonatomic,readonly) UILabel *position2; @property (nonatomic,readonly) UILabel *position3; @property (nonatomic,readonly) UILabel *score1; @property (nonatomic,readonly) UILabel *score2; @property (nonatomic,readonly) UILabel *score3;
14. Example code (continued) @synthesize badge; @synthesize badgeTitle; @synthesize name1; @synthesize name2; @synthesize name3; @synthesize position1; @synthesize position2; @synthesize position3; @synthesize score1; @synthesize score2; @synthesize score3;
15. There's more
16. //TODO: as of here, it is completely broken if ([gameView superview] != nil) { [[SoundBoard sharedSoundBoard] startMenuTune]; [menuViewController viewWillAppear:YES]; [gameViewController viewWillDisappear:YES]; [gameView removeFromSuperview]; [gameViewController viewDidDisappear:YES]; [menuViewController viewDidAppear:YES]; } else {
17. NSURL *cgiUrl = [NSURL URLWithString:POST_SCORE_URL]; NSMutableURLRequest *p = [NSMutableURLRequest requestWithURL:cgiUrl]; [p setTimeoutInterval:4]; [p setHTTPMethod:@"POST"]; [p setHTTPBody:requestData]; NSURLResponse *response = nil; NSError *error = nil; NSData *responseData = [NSURLConnection sendSynchronousRequest:p returningResponse:&response error:&error];
18. Memory Management 1. Add an instance variable 2. Add a property 3. Add a synthesize 4. Add a dealloc call
19. Memory Management 1. Add an instance variable 2. Add a property 3. Add a synthesize 4. Add a dealloc call
20. Memory Management
21. Animations [UIView beginAnimations:@"GameOver" context:NULL]; [UIView setAnimationDuration:0.3]; [UIView setAnimationRepeatCount:2]; [UIView setAnimationRepeatAutoreverses:YES]; // Call animateOtherStuff when the animation is done [UIView setAnimationDelegate:self]; [UIView setAnimationDidStopSelector: @selector(afterGameOverAnimation:finished:context:)];
22. Animations 2013 [UIView animateWithDuration:0.3 animations:^{ timesUp.alpha = 1; } completion:^(BOOL finished) { [self.milkGlass removeFromSuperview]; }]
24. The Good
25. If there's only one thing you'll remember Write code for the person after you
26. ▸ Write a lot of code ▸ Work with other people ▸ Write articles ▸ Read books and code
27. Write a lot of code ▸ Lots of production code ▸ Lots of throwaway code
28. Throwaway code
29. Collaborate ▸ With people who are better than you ▸ Or who aren't better than you
30. Write Forces you to think.
31. Absolute Knowledge
32. Perceived Knowledge
33. Strive to become better
34. Ship
35. Frameworks
36. 2013 ▸ Use ARC ▸ Use properties
37. Core Data
38. What prevents me from using Core Data at this point is my concern for scalability and performance. It’s possible I’m just being thick-headed. — Brent Simmons, 27 Sep 2013
39. So last weekend I switched from SQLite/FMDB to Core Data. This may come as a surprise. — Brent Simmons, 05 Oct 2013
41. Core Data ▸ Relationships ▸ Batching ▸ NSFetchedResultsControlle r ▸ Speed of use
42. Code style
43. My model was the NSURLConnectionDelegate Model should not know about the webservice
44. Using NSDictionary everywhere Create value objects
45. Value Objects @interface Person : NSObject @property (nonatomic,copy,readonly) NSString* name; @property (nonatomic,strong,readonly) NSDate* birthDate; @property (nonatomic,readonly) NSUInteger numberOfKids; - (instancetype)initWithName:(NSString*)name birthDate:(NSDate*)birthDate numberOfKids:(NSUInteger)numberOfKids; @end
46. Immutable Objects Use lots of them.
47. Deep code paths - (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex { if (alertState == submitScore && game.score > 0) { // 20 lines if (result != nil && [resultKeys containsObject:@"position"] && [resultKeys containsObject:@"neededPoints"] && [resultKeys containsObject:@"deviceHighscore"] && [resultKeys containsObject:@"personalHighscore"]) { // 10 lines if (position == 1) {
48. Deep code paths Pull out things into separate, well-named methods
49. Building everything in code Use Interface Builder
50. Writing fast code Write clear code, only optimize after measuring.
52. Tips and Tricks
53. Initializers [[HiscoresViewController alloc] initWithNibName:@"HiscoresView" bundle:nil]
54. Initializers // In HiscoresViewController.m - (id)init { self = [super initWithNibName:@"HiscoresView" bundle:nil]; if (self) { } return self; }
55. Use constants if (buttonIndex == 0)
56. Use constants if (buttonIndex == StartButton)
57. Pull out variable names if ([game state] == running || self.trainingMode)
58. Pull out variable names BOOL shouldPauseGame = [game state] == running || self.trainingMode; if (shouldPauseGame)
59. Pulling out protocols For example: UITableViewDataSource
60. @interface FetchedResultsControllerDataSource : NSObject <UITableViewDataSource, NSFetchedResultsControllerDelegate>
61. - (NSInteger)numberOfSectionsInTableView:(UITableView*)t { return self.fetchedResultsController.sections.count; }
62. - (NSInteger)tableView:(UITableView*)tableView numberOfRowsInSection:(NSInteger)sectionIndex { id<NSFetchedResultsSectionInfo> section; section = self.frc.sections[sectionIndex]; return section.numberOfObjects; }
63. - (UITableViewCell*)tableView:(UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath*)ip { id object = [self objectAtIndexPath:indexPath]; id cell = [tableView dequeueReusableCellWithIdentifier:ruI forIndexPath:ip]; [self.delegate configureCell:cell withObject:object]; return cell; }
64. Write small files I aim for a 100 line limit
65. Write small files 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
66. Write small files find . -name "*.m" -exec wc -l "{}" \; | sort -n
67. Keep your view controllers light This is the least reusable code you'll write
68. Use protocols instead of inheritance
70. The Bad
73. About me ▸ @chriseidhof ▸ http://www.objc.io ▸ http://chris.eidhof.nl
74. Questions?