Beginning iCloud Development

I will describe how iCloud works, what it is meant for, best practices to set up a project and implement synchronization strategies to replicate content on iOS and MacOSX devices.

http://mdevcon.com/2012/01/10/cesare-rocchi/

Transcript

1. Beginning iCloud development Rocchi Cesare
2. Outline What is iCloud? How does it work? Are there alternatives?
3. Who am I?
4. UX designer and developer
5. mnml
6. < is >
7. execution matters
8. lean approach
9. 1000 details coming together
10. Giveaway
11. 1 of the Wenderlich’s raywenderlich.com
13. iCloud Storyboards ARC OpenGL ES 2.0 News Stand Turn Based Gaming GameCenter API
14. twitter.com/_funkyboy cesarerocchi@me.com
15. Who are you?
16. What is iCloud?
17. 6028 Startown Rd, Maiden, NC
18. Stores and synchs stuff
19. It just works ...
20. ... when it works
22. Seamlessness can be a limit
23. Pros (for devs) No server setup No costs No rumination on synch
24. Cons (for devs) Stick to a synch model No http API No control on upload
25. Pros and Cons for users Expectation
26. Under the hood
28. Daemon Monitors changes Works on metadata Shreds files
29. Special folder, synched
30. Synched when “appropriate”
31. Appropriate Which OS? Which connection?
32. Placeholders
35. Information Structure Document Key-value CoreData
36. UIDocument
37. UIDocument NSFilePresenter Non-blocking read/write
39. -(void) openWithCompletionHandler:^(BOOL success) { }
40. - (BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError **)outError { }
41. @interface SMNote : UIDocument
42. @implementation SMNote - (BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError **)outError { if ([contents length] > 0) { self.myContent = [[NSString alloc] initWithBytes:[contents bytes] length:[contents length] encoding:NSUTF8StringEncoding]; } else { // Default content self.myContent = @"Empty"; } return YES; }
43. - (BOOL) saveToURL:(NSURL *)url forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) { }
44. - (id)contentsForType:(NSString *)typeName error:(NSError **)outError {}
45. - (id)contentsForType:(NSString *)typeName error:(NSError **)outError { return [NSData dataWithBytes:[self.myContent UTF8String] length:[self.myContent length]]; }
46. Autosave updateChangeCount: use the methods of the undoManager
47. @implementation SMNote @synthesize noteContent; // Called whenever the application reads data - (BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError **)outError { } // Called whenever the application (auto)saves the content - (id)contentsForType:(NSString *)typeName error:(NSError **)outError { }
48. Opening a document
49. Opening a document Build and run a query Wait for results Unfold results
50. #import "SMNote.h" @interface SMAppDelegate : UIResponder <UIApplicationDelegate> @property (strong, nonatomic) UIWindow *window; @property (strong, nonatomic) SMViewController *viewController; @property (strong) SMNote *doc; @property (strong) NSMetadataQuery *query; - (void)loadDocument; @end
51. NSMetadataQuery
52. - (void)loadDocument { NSMetadataQuery *query = [[NSMetadataQuery alloc] init]; _query = query; [query setSearchScopes:[NSArray arrayWithObject: NSMetadataQueryUbiquitousDocumentsScope]]; }
53. - (void)loadDocument { NSMetadataQuery *query = [[NSMetadataQuery alloc] init]; _query = query; [query setSearchScopes:[NSArray arrayWithObject: NSMetadataQueryUbiquitousDocumentsScope]]; NSPredicate *pred = [NSPredicate predicateWithFormat: @"%K == %@", NSMetadataItemFSNameKey, kFILENAME]; [query setPredicate:pred]; }
54. - (void)loadDocument { NSMetadataQuery *query = [[NSMetadataQuery alloc] init]; _query = query; [query setSearchScopes:[NSArray arrayWithObject: NSMetadataQueryUbiquitousDocumentsScope]]; NSPredicate *pred = [NSPredicate predicateWithFormat: @"%K == %@", NSMetadataItemFSNameKey, kFILENAME]; [query setPredicate:pred]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(queryDidFinish:) name:NSMetadataQueryDidFinishGatheringNotification object:query]; [query startQuery]; }
55. Asynchronous!
56. NSPredicate *pred = [NSPredicate predicateWithFormat: @"%K like 'Note_*'", NSMetadataItemFSNameKey];
57. - (void)queryDidFinish:(NSNotification *)notification { NSMetadataQuery *query = [notification object]; [query disableUpdates]; [query stopQuery]; [[NSNotificationCenter defaultCenter] removeObserver:self name:NSMetadataQueryDidFinishGatheringNotification object:query]; _query = nil; ! [self loadData:query]; }
58. - (void)loadData:(NSMetadataQuery *)query { if ([query resultCount] == 1) { NSMetadataItem *item = [query resultAtIndex:0]; NSURL *url = [item valueForAttribute:NSMetadataItemURLKey]; SMNote *doc = [[SMNote alloc] initWithFileURL:url]; } }
59. - (void)loadData:(NSMetadataQuery *)query { if ([query resultCount] == 1) { NSMetadataItem *item = [query resultAtIndex:0]; NSURL *url = [item valueForAttribute:NSMetadataItemURLKey]; SMNote *doc = [[SMNote alloc] initWithFileURL:url]; self.doc = doc; [self.doc openWithCompletionHandler:^(BOOL success) { if (success) { NSLog(@"iCloud document opened"); } else { NSLog(@"failed opening document from iCloud"); } }]; } }
60. else { NSURL *ubiq = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil]; NSURL *ubiquitousPackage = [[ubiq URLByAppendingPathComponent: @"Documents"] URLByAppendingPathComponent:kFILENAME]; SMNote *doc = [[SMNote alloc] initWithFileURL:ubiquitousPackage]; }
61. else { NSURL *ubiq = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil]; NSURL *ubiquitousPackage = [[ubiq URLByAppendingPathComponent: @"Documents"] URLByAppendingPathComponent:kFILENAME]; SMNote *doc = [[SMNote alloc] initWithFileURL:ubiquitousPackage]; self.doc = doc; [doc saveToURL: [doc fileURL] forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) { if (success) { [doc openWithCompletionHandler:^(BOOL success) { NSLog(@"new document opened from iCloud"); }]; } }]; }
62. - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { ... [self.window makeKeyAndVisible]; NSURL *ubiq = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil]; if (ubiq) { NSLog(@"iCloud access at %@", ubiq); [self loadDocument]; } else { NSLog(@"No iCloud access"); } return YES; }
63. - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { ... [self.window makeKeyAndVisible]; NSURL *ubiq = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil]; if (ubiq) { NSLog(@"iCloud access at %@", ubiq); [self loadDocument]; } else { NSLog(@"No iCloud access"); } return YES; }
64. - (void)viewDidLoad { [super viewDidLoad]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(dataReloaded:) name:@"noteModified" object:nil]; } - (void)dataReloaded:(NSNotification *)notification { self.doc = notification.object; self.noteView.text = self.doc.noteContent; }
65. Switching on/off
66. - (NSURL *) localNotesURL { return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; } - (NSURL *) ubiquitousNotesURL { return [[[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil] URLByAppendingPathComponent:@"Documents"]; }
67. - (void) setNoteUbiquity { NSURL *baseUrl = [self localNotesURL]; if (_useiCloud) baseUrl = [self ubiquitousNotesURL]; NSURL *destUrl = [baseUrl URLByAppendingPathComponent: [note.fileURL lastPathComponent]]; [[NSFileManager defaultManager] setUbiquitous:_useiCloud itemAtURL:note.fileURL destinationURL:destUrl error:NULL]; } Don’t call it on the main thread!
68. - (void) startMigration { NSOperationQueue *iCloudQueue = [NSOperationQueue new]; NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(setNoteUbiquity) object:nil]; [iCloudQueue addOperation:op]; }
69. Custom documents
70. @interface SMNote : NSObject <NSCoding> @property (copy, nonatomic) NSString *noteId; @property (copy, nonatomic) NSString *noteContent; @property (strong, nonatomic) NSDate *createdAt; @property (strong, nonatomic) NSDate *updatedAt; @end
71. #import "SMNote.h" @interface SMNotesDocument : UIDocument @property (nonatomic, strong) NSMutableArray *entries; @property (nonatomic, strong) NSFileWrapper *fileWrapper; @end
72. #import "SMNote.h" @interface SMNotesDocument : UIDocument @property (nonatomic, strong) NSMutableArray *entries; @property (nonatomic, strong) NSFileWrapper *fileWrapper; @end
73. - (id)contentsForType:(NSString *)typeName error:(NSError **)outError { NSMutableDictionary *w = [NSMutableDictionary dictionary]; NSMutableData *data = [NSMutableData data]; NSKeyedArchiver *arch = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; [arch encodeObject:_entries forKey:@"entries"]; [arch finishEncoding]; }
74. - (id)contentsForType:(NSString *)typeName error:(NSError **)outError { NSMutableDictionary *w = [NSMutableDictionary dictionary]; NSMutableData *data = [NSMutableData data]; NSKeyedArchiver *arch = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; [arch encodeObject:_entries forKey:@"entries"]; [arch finishEncoding]; NSFileWrapper *entriesWrapper = [[NSFileWrapper alloc] initRegularFileWithContents:data]; [w setObject:entriesWrapper forKey:@"notes.dat"]; // add other wrappers if you like NSFileWrapper *res = [[NSFileWrapper alloc] initDirectoryWithFileWrappers:w]; return res; }
75. - (BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError **)outError { NSFileWrapper *wrapper = (NSFileWrapper *)contents; NSDictionary *d = [wrapper fileWrappers]; NSFileWrapper *entriesWrap = [d objectForKey:@"notes.dat"]; }
76. - (BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError **)outError { NSFileWrapper *wrapper = (NSFileWrapper *)contents; NSDictionary *d = [wrapper fileWrappers]; NSFileWrapper *entriesWrap = [d objectForKey:@"notes.dat"]; NSData *data = [entriesWrap regularFileContents]; NSKeyedUnarchiver *arch = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; _entries = [arch decodeObjectForKey:@"entries"]; // Notify the view }
77. Uniform Type Identifier
79. Key-value
80. Key-value 64kb :(
81. - (void) saveNoteAsCurrent { [[NSUbiquitousKeyValueStore defaultStore] setString:self.currentNote.noteId forKey:@"com.studiomagnolia.currentNote"]; [[NSUbiquitousKeyValueStore defaultStore] synchronize]; }
82. - (void) saveNoteAsCurrent { [[NSUbiquitousKeyValueStore defaultStore] setString:self.currentNote.noteId forKey:@"com.studiomagnolia.currentNote"]; [[NSUbiquitousKeyValueStore defaultStore] synchronize]; } NSString *currentNoteId = [[NSUbiquitousKeyValueStore defaultStore] stringForKey: @"com.studiomagnolia.currentNote"];
83. NSUbiquitousKeyValueStore* store = [NSUbiquitousKeyValueStore defaultStore]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(updateCurrentNoteIfNeeded:) name:NSUbiquitousKeyValueStoreDidChangeExternallyNotification object:store]; [store synchronize];
84. Conflict Resolution
85. Conflict Resolution Up to the dev documentState
86. DocumentStates UIDocumentStateNormal UIDocumentStateClosed UIDocumentStateInConflict UIDocumentStateSavingError UIDocumentStateEditingDisabled
87. UIDocumentStateChangedNotification
88. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(noteHasChanged:) name:UIDocumentStateChangedNotification object:nil];
89. UIDocumentState s = [n documentState]; switch (s) { case UIDocumentStateNormal: NSLog(@"Everything is fine"); break; case UIDocumentStateInConflict: NSLog(@"There is a conflict"); break; ... default: NSLog(@"Unknown state"); break; }
90. UI conflict vs iCloud conflict
91. Resolution policy last wins prompt user automatic merge
92. Resolution policy last wins prompt user automatic merge NSFileVersion
93. NSError *err; NSURL *url = [[NSFileManager defaultManager] URLForPublishingUbiquitousItemAtURL:[self.currentNote fileURL] expirationDate:&expirationInOneHourSinceNow error:&err];
95. Tips & Tricks
96. Patience!
97. Test on wireless & 3G
98. Regenerate provisioning
99. Delete previous data
101. Restart device
102. API throttle!
103. App policy Be gentle with storage <App_home>/tmp <App_home>/Library/Caches/
104. “To iCloud or not to iCloud?”
105. “To iCloud or not to iCloud?”
106. Alternatives
107. Alternatives dropbox parse.com cloudmine stackmob
108. Dropbox documents authentication no notifications
109. Dropbox other platforms no CR (revision #) expectation
110. Parse
111. Parse ORM approach Still beta No cost of infrastructure
112. Parse Pay as you use Limit of objects/mo Limit of calls/mo
113. PFObject *note = [PFObject objectWithClassName:@"Note"]; [note setObject:@"Ciao" forKey:@"title"]; [note setObject:@"Note on Parse" forKey:@"content"]; [note save]; //[note saveInBackground]; //[note saveEventually];
114. [note saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) { if (error) { NSLog(@"Note not saved"); } else { NSLog(@"Note saved successfully"); } }];
115. Parse Other platforms REST API Push notifications data browser
116. curl -X POST \ -H "X-Parse-Application-Id: ${APPLICATION_ID}" \ -H "X-Parse-REST-API-Key: ${REST_API_KEY}" \ -H "Content-Type: application/json" \ -d '{"note": 001, "title": "Ciao", "content": “Note on parse” }' \ https://api.parse.com/1/classes/GameScore
117. PFObject *note = [PFObject objectWithClassName:@"Note"]; [note setObject:@"Ciao" forKey:@"title"]; [note setObject:@"Note on parse" forKey:@"content"]; PFObject *myTag = [PFObject objectWithClassName:@"Tag"]; [myTag setObject:@"important" forKey:@"tagName"]; // Add a relation [note setObject:myTag forKey:@"tag"]; // Saves both [note saveInBackground];
118. Recap UIDocument Key-Value store Alternatives
119. Contact twitter.com/_funkyboy cesarerocchi@me.com http://studiomagnolia.com