Beginning iCloud Development

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Beginning iCloud development Rocchi Cesare

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Outline What is iCloud? How does it work? Are there alternatives?

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Who am I?

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UX designer and developer

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mnml

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< is >

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execution matters

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lean approach

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1000 details coming together

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Giveaway

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1 of the Wenderlich’s raywenderlich.com

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iCloud Storyboards ARC OpenGL ES 2.0 News Stand Turn Based Gaming GameCenter API

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twitter.com/_funkyboy [email protected]

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Who are you?

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What is iCloud?

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6028 Startown Rd, Maiden, NC

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Stores and synchs stuff

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It just works ...

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... when it works

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Seamlessness can be a limit

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Pros (for devs) No server setup No costs No rumination on synch

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Cons (for devs) Stick to a synch model No http API No control on upload

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Pros and Cons for users Expectation

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Under the hood

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Daemon Monitors changes Works on metadata Shreds ﬁles

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Special folder, synched

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Synched when “appropriate”

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Appropriate Which OS? Which connection?

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Placeholders

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Information Structure Document Key-value CoreData

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UIDocument

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UIDocument NSFilePresenter Non-blocking read/write

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-(void) openWithCompletionHandler:^(BOOL success) { }

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- (BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError **)outError { }

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@interface SMNote : UIDocument

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@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; }

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- (BOOL) saveToURL:(NSURL *)url forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) { }

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- (id)contentsForType:(NSString *)typeName error:(NSError **)outError {}

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- (id)contentsForType:(NSString *)typeName error:(NSError **)outError { return [NSData dataWithBytes:[self.myContent UTF8String] length:[self.myContent length]]; }

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Autosave updateChangeCount: use the methods of the undoManager

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@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 { }

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Opening a document

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Opening a document Build and run a query Wait for results Unfold results

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#import "SMNote.h" @interface SMAppDelegate : UIResponder @property (strong, nonatomic) UIWindow *window; @property (strong, nonatomic) SMViewController *viewController; @property (strong) SMNote *doc; @property (strong) NSMetadataQuery *query; - (void)loadDocument; @end

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NSMetadataQuery

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- (void)loadDocument { NSMetadataQuery *query = [[NSMetadataQuery alloc] init]; _query = query; [query setSearchScopes:[NSArray arrayWithObject: NSMetadataQueryUbiquitousDocumentsScope]]; }

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- (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]; }

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Asynchronous!

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NSPredicate *pred = [NSPredicate predicateWithFormat: @"%K like 'Note_*'", NSMetadataItemFSNameKey];

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- (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]; }

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- (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"); } }]; } }

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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"); }]; } }]; }

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- (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; }

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- (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; }

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Switching on/off

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- (NSURL *) localNotesURL { return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; } - (NSURL *) ubiquitousNotesURL { return [[[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil] URLByAppendingPathComponent:@"Documents"]; }

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- (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!

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- (void) startMigration { NSOperationQueue *iCloudQueue = [NSOperationQueue new]; NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(setNoteUbiquity) object:nil]; [iCloudQueue addOperation:op]; }

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Custom documents

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@interface SMNote : NSObject @property (copy, nonatomic) NSString *noteId; @property (copy, nonatomic) NSString *noteContent; @property (strong, nonatomic) NSDate *createdAt; @property (strong, nonatomic) NSDate *updatedAt; @end

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#import "SMNote.h" @interface SMNotesDocument : UIDocument @property (nonatomic, strong) NSMutableArray *entries; @property (nonatomic, strong) NSFileWrapper *fileWrapper; @end

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#import "SMNote.h" @interface SMNotesDocument : UIDocument @property (nonatomic, strong) NSMutableArray *entries; @property (nonatomic, strong) NSFileWrapper *fileWrapper; @end

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- (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; }

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- (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 }

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Uniform Type Identiﬁer

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Key-value

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Key-value 64kb :(

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- (void) saveNoteAsCurrent { [[NSUbiquitousKeyValueStore defaultStore] setString:self.currentNote.noteId forKey:@"com.studiomagnolia.currentNote"]; [[NSUbiquitousKeyValueStore defaultStore] synchronize]; } NSString *currentNoteId = [[NSUbiquitousKeyValueStore defaultStore] stringForKey: @"com.studiomagnolia.currentNote"];

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NSUbiquitousKeyValueStore* store = [NSUbiquitousKeyValueStore defaultStore]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(updateCurrentNoteIfNeeded:) name:NSUbiquitousKeyValueStoreDidChangeExternallyNotification object:store]; [store synchronize];

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Conﬂict Resolution

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Conﬂict Resolution Up to the dev documentState

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DocumentStates UIDocumentStateNormal UIDocumentStateClosed UIDocumentStateInConflict UIDocumentStateSavingError UIDocumentStateEditingDisabled

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UIDocumentStateChangedNotification

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[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(noteHasChanged:) name:UIDocumentStateChangedNotification object:nil];

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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; }

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UI conﬂict vs iCloud conﬂict

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Resolution policy last wins prompt user automatic merge

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Resolution policy last wins prompt user automatic merge NSFileVersion

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NSError *err; NSURL *url = [[NSFileManager defaultManager] URLForPublishingUbiquitousItemAtURL:[self.currentNote fileURL] expirationDate:&expirationInOneHourSinceNow error:&err];

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Tips & Tricks

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Patience!

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Test on wireless & 3G

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Regenerate provisioning

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Delete previous data

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Restart device

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API throttle!

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App policy Be gentle with storage /tmp /Library/Caches/

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“To iCloud or not to iCloud?”

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“To iCloud or not to iCloud?”

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Alternatives

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Alternatives dropbox parse.com cloudmine stackmob

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Dropbox documents authentication no notiﬁcations

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Dropbox other platforms no CR (revision #) expectation

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Parse

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Parse ORM approach Still beta No cost of infrastructure

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Parse Pay as you use Limit of objects/mo Limit of calls/mo

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PFObject *note = [PFObject objectWithClassName:@"Note"]; [note setObject:@"Ciao" forKey:@"title"]; [note setObject:@"Note on Parse" forKey:@"content"]; [note save]; //[note saveInBackground]; //[note saveEventually];

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[note saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) { if (error) { NSLog(@"Note not saved"); } else { NSLog(@"Note saved successfully"); } }];

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Parse Other platforms REST API Push notiﬁcations data browser

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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

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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];