The Evolution of a Cocoa Programmer

Transcript

1. The evolution of a Cocoa Programmer Chris Eidhof Mobile Central Europe 2014
2. Hashtags #mceconf #mce-evolution
5. commit c416c1d259bddaa74833e6df5acd770f85622293 Author: Chris Eidhof <ce@tupil.com> Date: Wed Jan 7 11:54:34 2009 +0100 Empty project
6. I thought I was a pretty good programmer
7. I knew PHP, Ruby and Haskell
8. How hard can it be?
9. 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; }
10. 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;
11. 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;
12. There's more
13. //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 {
14. 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];
15. How did I get better?
16. If there's only one thing you'll remember Write code for the person after you
17. EDD Embarassment-Driven Development
18. —Write a lot of code —Work with other people —Write articles —Read books and code
19. Write a lot of code —Lots of production code —Lots of throwaway code
21. Collaborate —With people who are better than you —Or who aren't better than you
22. Write Forces you to think.
23. Learn your frameworks —Use Core Data —Use UITableViewController —Use NSURLSession
24. Absolute Knowledge
25. 2014 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 1 2 3 4 5 Time How much I know
26. Perceived Knowledge
27. 2014 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 1 2 3 4 5 Time How much I know
28. Strive to become better
29. Ship
30. Writing better code —Quick wins —Value Objects —Lighter View Controllers
31. Quick Wins
32. I used to do this: if (buttonIndex == 0)
33. I used to do this: if (buttonIndex == 0) instead, now I write if (buttonIndex == StartButton)
34. I used to write this: if ([game state] == running || self.trainingMode)
35. I used to write this: if ([game state] == running || self.trainingMode) Now I write this: BOOL shouldPauseGame = game.state == running || self.trainingMode; if (shouldPauseGame)
36. Write small files I aim for 100-150 lines
37. Write small files 325 ./THStyleSheet.m 279 THSkillboxView.m 263 THCardsViewController.m 243 THTimeLineView.m 221 THScreeningBarViewController.m 192 THEditPriorityViewController.m 185 User+Extensions.m 183 THScreenInstanceViewController.m 183 THRootViewController.m 179 THUserScreenInstancesController.m 168 THPriorityTimelineCollectionController.m 155 UIView+Extensions.m 155 NSArray+Extensions.m 154 THZoomingNavigationController.m
38. Write small files find . -name "*.m" -exec wc -l "{}" \; | sort -n
39. Use protocols instead of class inheritance They are much more flexible and make for clearer code.
40. 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
41. Deep code paths Pull out things into separate, well-named methods
42. Don't write fast code Optimize for readability
43. Really learn Interface Builder This makes prototyping much faster
44. Learn your frameworks
45. 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
46. So last weekend I switched from SQLite/FMDB to Core Data. This may come as a surprise. — Brent Simmons, 05 Oct 2013
47. Core Data —Relationships —Batching —NSFetchedResultsController —Speed of use
48. Value Objects
49. I used NSDictionary for everything NSDate* birthDate = [NSDate dateWithTimeIntervalSince1970:131855*3600]; NSDictionary* person = @{ @"name": @"Chris", @"birthdate": birthDate, @"numberOfKids": @0 };
50. Problems with NSDictionary —It's not typechecked —It might be mutated
51. A first step @interface Person : NSObject @property (nonatomic,copy) NSString* name; @property (nonatomic) NSDate* birthDate; @property (nonatomic) NSUInteger numberOfKids; @end
52. Mutation Sometimes mutation is very handy. Most of the times it will bite you.
53. @interface Person : NSObject @property (nonatomic,readonly) NSString* name; @property (nonatomic,readonly) NSDate* birthDate; @property (nonatomic,readonly) NSUInteger numberOfKids; - (instancetype) initWithName:(NSString*)name birthDate:(NSDate*)birthDate numberOfKids:(NSUInteger)numberOfKids; @end
54. Value Objects —Use lots of them. —Make them immutable.
55. Lighter View Controllers
56. Keep your view controllers light This is the least reusable code you'll write
57. What can you do? —Smarter views —Smarter models —Use view controller transitions —Use categories to populate views —Pull out protocols
58. Use categories to populate views - (UITableViewCell*)tableView:(UITableView*)tv cellForRowAtIndexPath:(NSIndexPath*)ip { User *user = [self userAtIndexPath:ip]; MyCell *cell = [tv dequeueReusableCellWithIdentifier:ruI forIndexPath:ip]; cell.textLabel.text = user.name; cell.imageView.image = user.avatar; .... }
59. Use categories to populate views @interface MyCell (ConfigureForUser) - (void)configureForUser:(User *)user; @end
60. Use categories to populate views - (void)configureForUser:(User *)user { cell.textLabel.text = user.name; cell.imageView.image = user.avatar; ... }
61. Use categories to populate views —Your view controller is a bit simpler —Your population code can be reused ... —But now your view knows about your model. Sort of.
62. Pulling out protocols
63. Pulling out protocols For example: UITableViewDataSource
64. Creating a separate data source object @interface FetchedResultsControllerDataSource : NSObject <UITableViewDataSource, NSFetchedResultsControllerDelegate>
65. Creating a separate data source object - (NSInteger)numberOfSectionsInTableView: (UITableView*)t { return self.fetchedResultsController.sections.count; }
66. Creating a separate data source object - (NSInteger)tableView:(UITableView*)tableView numberOfRowsInSection:(NSInteger)sectionIndex { id<NSFetchedResultsSectionInfo> section; section = self.frc.sections[sectionIndex]; return section.numberOfObjects; }
67. Creating a separate data source object Working with the delegate - (UITableViewCell*)tableView:(UITableView*)tv cellForRowAtIndexPath:(NSIndexPath*)ip { id object = [self objectAtIndexPath:indexPath]; id cell = [tv dequeueReusableCellWithIdentifier:ruI forIndexPath:ip]; [self.delegate configureCell:cell withObject:object]; return cell; }
68. Advantages of a separate data source —Lighter view controller —Testable —Reusable And you can do this for other protocols, too
69. A separate data source —NSArrayDataSource —NSFRCollectionViewController —...
70. So.... —Write for the person after you —Know your frameworks —Keep your view controllers light
71. Commercial Break
73. Questions? @chriseidhof