Cocoa Touch: The Good, The Bad and The Ugly

Transcript

1. None

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
5. None
6. None

7. I thought I was a pretty good programmer

8. I knew PHP, Ruby and Haskell

9. How hard can it be?

10. None

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]; }]
23. None

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
40. None

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.

51. None

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

69. None

70. The Bad

71. None
72. None

73. About me ▸ @chriseidhof ▸ http://www.objc.io ▸ http://chris.eidhof.nl

74. Questions?