The document explores Core Data and its integration with iCloud, detailing concepts such as managed object contexts, persistent stores, and fetch requests. It highlights the advantages of using Core Data, including its object-oriented storage model and managing relationships between data entities. Additionally, the document covers iCloud features such as container storage, key/value storage, and the entitlement process required for seamless data synchronization across devices.

1. CoreData:
Connecting to the Cloud
an Improvement
Scott M. Neal
smn@automationgarden.com
smn.mg@acmefoo.org
scottmneal@gmail.com
© 2012-2014 AutomationGarden
1

2. Topics: tonight
Core Data Review
iCloud
2
2

3. Core Data Brief Review
3
3

4. Why CoreData?
Provides an OO layer for persistent storage
• Apple avoids the word “database”
don’t need to know SQL
• YouHardcoded, hacked SQL in apps is a Royal PITA to
• maintain
Why not just use Defaults?
• Defaults doesn’t know about relationships
• The OSX defaults command has limited access to
values below the top level
• PlistBuddy overcomes this
up to you to decide to use
or Core
• It’sbut once you know Core Data,Defaults to leave...Data
it’s hard
•
4
4

5. Entity: Review
Default subclass of NSManagedObject
Kinda-sorta like a row in a DB table
• but much more OO
Can create custom Entities which utilize Inheritance
Hierarchy
• Group Cats and Dogs under shared abstract superclass
Mammals
• Relationships
5
5

6. Entity can contain:
• Attribute on value class
• type based
• Relationship
types
•
•
•
•
one-to-one
one-to-many
many-to-many (via “join table”)
• Returned to caller as an NSSet (unsorted)
relationships
• Inverserules
• DeleteAction/Nullify/Cascade/Deny
No
•
• Fetched Property as an NSArray
Returned to caller
•
Can also store fetch request(s) with an entity
6
6

7. Core Data Stack: Review
is
the center of most
everything we’ll need
to do with Core Data
NSManagedObjectContext
NSManagedObjectContext
NSPersistentStoreCoordinator
talks directly with
“database” store
• 1 instance per store
• Can handle multiple
concurrent
instances of
NSMangedObjectContext
NSPersistentStoreCoordinator
NSManagedObjectModel
is a
compiled version of
the .xcdatamodel you
create in Xcode
NSManagedObjectModel
sqlite, xml, ...
NSPersistentStore
is an
object representation
of data store
NSPersistentStore
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7

8. NSManagedObjectContext
The “center of the universe”
NOT thread safe by default
• http://stackoverflow.com/questions/10593735/
making-core-data-thread-safe
Needed for
• Insertion of new NSManagedObject (or subclasses)
• Fetching of NSManagedObject (or subclasses)
Handled for you automatically when you use Bindings
to wire-up interface to model
• Alas, no bindings on iOS (currently...)
8
8

9. NSPersistentStore*
Each “database” store has one NSPersistentStore
instance (and ONLY one) associated with it
Each NSPersistentStore has one (and ONLY one)
NSPersistentStoreCoordinator
• communicates with NSPersistentStore
• Uses NSManagedObjectModel to know how to OO-ify
the underlying store into a Core Data
NSManagedObjectContext-friendly way
Multiple NSManagedObjectContext instances use a
single NSPersistentStoreCoordinator
• This ensures data store consistency
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9

10. NSManagedObjectModel
A compiled version of the .xcdatamodel you create in
Xcode
Often abbreviated MOM (Managed Object Model)
Contains a complete description of all Entities,
including their properties (attributes and
relationships), fetch requests, fetch properties, etc.
You may assign a version to a MOM via an identifier
within the MOM or a key within the MOM’s userInfo
• “v1.1”, or “build38release29a” or whatever you want
MOMs can be migrated forward
• Difficult to migrate backwards
10
10

11. Guides to Fetching &
Predicates
Apple’s guides:
• http://developer.apple.com/library/mac/
#documentation/Cocoa/Conceptual/CoreData/
•
Articles/cdFetching.html
http://developer.apple.com/library/mac/
#documentation/Cocoa/Conceptual/Predicates/
predicates.html
• Predicates not solely for core data
Spotlight
•
•
•
In-memory filtering
...
11
11

12. Predicate Basics
Most common way to create predicates:
predicateWithFormat:
• The predicate format string syntax is different from
regular expression syntax
• The regular expression syntax is defined by the ICU—see
http://www.icu-project.org/userguide/regexp.html
can use regex with MATCHES
• YouThe left hand expression equals the right hand expression
•
using a regex-style comparison according to ICU v3
diacritic
• String comparisons are by default case andthe key
sensitive. You can modify an operator using
characters c and d within square braces to specify case
and diacritic insensitivity respectively, for example
firstName BEGINSWITH[cd] $FIRST_NAME.
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12

13. Predicate Basics
Have the Predicate Format String Syntax doc handy
• http://developer.apple.com/library/mac/
#documentation/Cocoa/Conceptual/Predicates/
Articles/pSyntax.html#//apple_ref/doc/uid/
TP40001795-CJBDBHCB
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13

14. Review:
Fetching with Core Data
NSManagedObjectContext *moc = [self managedObjectContext];
NSEntityDescription *entityDescription = [NSEntityDescription
entityForName:@"Employee" inManagedObjectContext:moc];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:entityDescription];
// Set example predicate and sort orderings...
NSNumber *minimumSalary = ...;
NSPredicate *predicate = [NSPredicate predicateWithFormat: @"(lastName
LIKE[c] 'Lindsay') AND (salary > %@)", minimumSalary];
[request setPredicate:predicate];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]
initWithKey:@"firstName" ascending:YES];
[request setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
NSError* error = nil;
NSArray* array = [moc executeFetchRequest:request error:&error];
if (nil == array) || (nil != error)
{
// Deal with error...
}
...
14
14

15. Review:
Insert/Save in Core Data
NSManagedObjectContext *moc = [self managedObjectContext];
NSManagedObject *aUser = [NSEntityDescription
insertNewObjectForEntityForName:@"User"
inManagedObjectContext:moc];
[aUser setValue:@"Scott" forKey:@"name"];
[aUser setValue:@"Portland" forKey:@"city"];
[aUser setValue:@"Oregon" forKey:@"state"];
NSError *error;
if (![moc save:&error])
{
NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
}
15
15

16. Demo Apps:
Road Trip
- From “iOS Cloud Development for Dummies”
• Download examples (warts and all) from
- http://www.dummies.com/go/iosclouddev
Example iOS7
- http://ossh.com.au/design-and-technology/softwaredevelopment/sample-library-style-ios-core-data-appwith-icloud-integration/
Peruse ADC for anything interesting
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17. iCloud
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18. iCloud
iCloud: serves iOS and Mac/PC devices
• Multi-Application Ecosystem
Can store on iCloud
• Key-Value Storage NSUserDefaults
• Cloud version of
• Container Storage
Document
•
• File
• Package
• Core Data
Document Service
• Uses automagically handle changes to/from iCloud servers
• to
iOS 5 or later
• Introduced WWDC2011, released October 2011
• sorry <=iOS4...
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18

19. iCloud
Utilizes Transaction Logs
• entire data is not copied each time
Developer doesn’t worry about
• making network connection
• configuring iCloud itself
Programmer registers for notifications to know when
changes have occurred in the cloud
• and handles appropriately
Only works on devices, not on simulator
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19

20. iCloud Entitlement
Uses Entitlement called “Ubiquity Container”
• Entitlement named NS*Ubiquitous
• not NS*Cloud or UI*Cloud
• Default definition uses your TeamID (or IndividualID)
and your BundleID
• Seen when logged into Apple Developer Member Center
• example URL:
• /var/mobile/Library/Mobile Documents/
J3K73N7L25.senseption.com.neal.RoadTrip/
All need to be coordinated:
• Provisioning Profile
• AppID
• BundleID
• com.apple.developer.ubiquity-kvstore-identifier
• com.apple.developer.ubiquity-container-identifiers
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20

21. iCloud Entitlement Process
1. On Apple Developer Member Center, enable iCloud
entitlement/service/capability (for new or old app)
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22. iCloud Entitlement Process
2. Create and Download Provisioning Profile
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23. iCloud Entitlement Process
3. Drag Provisioning Profile into Xcode Organizer (if
not done automatically)
NOT here
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24. iCloud Entitlement Process
4. Enable entitlements/capabilities in the project (if
not already done)
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25. iCloud Key/Value Storage
Not CoreData specific, but a nice feature
Conflict resolution
• Simple: last change wins
Works even when iCloud not enabled
Stats
• Up to 1024 keys
• 1MB data per application
• Up to 15 requests per 90 seconds
Just like NSDefaults, do NOT store any passwords here
• encrypted or otherwise...
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26. iCloud Key/Value Storage
// Get an app’s default store
NSUbiquitousKeyValueStore* kvStore = [NSUbiquitousKeyValueStore
defaultStore];
// Register notification to see if data on the cloud has changed
[[NSNotificationCenter defaultCenter] addObserver:self
selector: @selector(ubiquitousKeyValueStoreDidChange:)
name: NSUbiquitousKeyValueStoreDidChangeExternallyNotification
object: kvStore];
// Values not stored to/from iCloud until you synchronize
[kvStore synchronize];
// Store a value in the kv store
[keyStore setString:@”Saved String” forKey:@"MyString"];
// Values not stored to/from iCloud until you synchronize
[kvStore synchronize];
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26

27. iCloud Key/Value Storage
Reason that notification was fired is returned in notification
• Initial download from iCloud
• Other device modified data (“push”)
• Over iCloud quota
// Get an app’s default store
- (void)ubiquitousKeyValueStoreDidChange:(NSNotification* theNotif)
{
" NSDictionary* userInfo = [notification userInfo];
// get reason for change
" int reason = [[userInfo
objectForKey:NSUbiquitousKeyValueStoreChangeReasonKey] intValue];
// get the changed keys--ONLY the changed keys
" NSArray* changedKeys = [userInfo
objectForKey:NSUbiquitousKeyValueStoreChangedKeysKey];
// store the changed values locally
...
}
27
27

28. iCloud Container Storage
Application Container
• File Storage area that is app-specific
• “Sandbox”
Ubiquity Container
• iCloud-specific file storage area
Data (whether document or core) is broken up sort-oflike a tiled image into chunks
• All chunks moved upon first upload to iCloud
• Only changed chunks moved when changes made
28
28

29. iCloud Container Storage
Metadata always pushed via NSMetadataQuery
• Clients always know what documents are available to
them from iCloud
Client pulls what it wants/needs
• Mac OS X: everything
• iOS: app makes request
Data transferred peer-to-peer when possible
Automatic conflict resolution
• You can also peruse UIDocumentStateInConflict
URL Publishing
• Can include as email attachment rather than the
document itself
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29

30. iCloud Container Storage
Container URL
• The network path to desired document
• Avoid getting on the main thread
To Check for iCloud availability:
• iOS 6 / Mtn Lion (or later):
id token = [[NSFileManager defaultManager]
ubiquityIdentityToken];
if(token) ...
• iOS 5 / Lion (or later):
NSURL *ubiq = [[NSFileManager defaultManager]
"
URLForUbiquityContainerIdentifier:nil];
if (!ubiq) ...
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30

31. iCloud Container Storage
Asynchronous method
// Register notification to see if iCloud available
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@(handleUbiquityIdentityChanged:)
name:NSUbiquityIdentityDidChangeNotification object:nil];
// Get container URL on not-the-main thread
dispatch_async(
dispatch_get_global_queue(DISPATCH_PRIORITY_QUEUE_DEFAULT, 0),
^{
NSURL *containerURL = [[NSFileManager defaultManager]
"
URLForUbiquityContainerIdentifier:nil];
}
);
31
31

32. iCloud Document w/o
Core Data
UIDocument / NSDocument
1. Determine whether iCloud is enabled on device by
sending
• [NSFileManager URLForUbiquityContainerIdentifier:]
Will return something like
•
•
N42E42A42L.com.neal.RoadTrip
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32

33. iCloud Document w/o
Core Data
2. Add file presenters
• Adopt NSFilePresenter protocol
changes through
• Make allfile for editing NSFileCoordinator object
locks
•
background
• preventstime your code iCloud processes from modifying file
at same
is
• UIDocument already conforms to NSFilePresenter
3. Explicitly move your files to iCloud
• Use value returned in step 1 with
• [NSFileManager
setUbiquitous:itemAtURL:destinationURL:error]
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33

34. iCloud Document w/o
Core Data
4. Handle version conflicts for a file
the same file
• When multiple applications/devices saveiCloud stores
to the same container at the same time,
both and lets the user decide which is the “right one”
5. Use running NSMetaDataQuery objects to receive
notifications from applications/devices as files are
added or removed
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34

35. iCloud Document w/o
Core Data
6. Handle cases where files are in iCloud but are not
fully downloaded to local application/device
• File is considered fully downloaded when the
application:
• Attempts to access the file
startDownloadingUbiquitousItemAtURL:error
• Sends theto NSFileManager
message
For a user, cloud ignorance is bliss--they just want their
document
• And you need to track/handle these cases yourself
35
35

36. iCloud with Core Data
Database, not Document
Core Data Storage remains local
Core Data Stores that support
• change logs
• sqlite
• full file transfer
• xml
• binary
UIManagedDocument & NSPersistentStore
• See http://developer.apple.com/library/ios/
#releasenotes/DataManagement/RN-iCloudCoreData/
_index.html
• NSPersistentDocument not supported on iCloud
iCloud itself is NOT a Persistent Store--works outside of
Core Data
36
36

37. iCloud with Core Data
Features
•
•
•
•
•
Per record conflict resolution
Three-way merge
Incremental changes only
Asynchronous Import
Lightweight schema migration
• versioning
Multiple “Local” stores as a best practice
• One to hold data that doesn’t belong in the cloud
• One to act as a “cache” to iCloud
• Decide if your iCloud store should be available all times
Fallback Store should exist in case user doesn’t
enable/use iCloud
Use Core Data Migration to pre-populate new store
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37

38. iCloud with Core Data
Use Data Model Configurations to allow Core Data to
split entities across multiple stores
• iCloud vs. Local
Single Managed Object Context will “do the right thing”
38
38

39. iCloud with Core Data
//add the store, use the "LocalConfiguration" to make sure
state entities all end up in this store and that no iCloud
entities end up in it
_localStore = [_psc
addPersistentStoreWithType:NSSQLiteStoreType
configuration:@"LocalConfig"
URL:storeURL
options:nil
error:&localError];
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39

40. iCloud with Core Data
- (BOOL)loadiCloudStore:(NSError * __autoreleasing *)error
{
BOOL success = YES;
NSError *localError = nil;
NSFileManager *fm = [[NSFileManager alloc] init];
_ubiquityURL = [fm URLForUbiquityContainerIdentifier:nil];
NSURL *iCloudStoreURL = [self iCloudStoreURL];
NSURL *iCloudDataURL = [self.ubiquityURL
URLByAppendingPathComponent:@"iCloudData"];
NSDictionary *options = @{
NSPersistentStoreUbiquitousContentNameKey : @"iCloudStore",
NSPersistentStoreUbiquitousContentURLKey : iCloudDataURL };
_iCloudStore = [self.psc
addPersistentStoreWithType:NSSQLiteStoreType
configuration:@"CloudConfig"
URL:iCloudStoreURL
options:options
error:&localError];
...
40
40

41. iCloud with Core Data
1. Provide a value for
NSPersistentStoreUbiquitousContentNameKey
2. Provide a value for
NSPersistentStoreUbiquitousContentURLKey
• the value that we saw earlier which was a URL path,
including TeamID and BundleID like
• N42E42A42L.com.neal.RoadTrip
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41

42. iCloud with Core Data
NSFileManager* fileManager = [NSFileManager defaultManager];
NSURL* persistentStoreUbiquitousContentURL = [fileManager
URLForUbiquityContainerIdentifier:nil];
NSString* ubiquityContainerIdentifierPath =
[[persistentStoreUbiquitousContentURL path]
stringByAppendingPathComponent:@"RoadTripSharedPointOfInterest"
];
persistentStoreUbiquitousContentURL = [NSURL
fileURLWithPath:ubiquityContainerIdentifierPath];
options = [NSDictionary dictionaryWithObjectsAndKeys:[NSString
stringWithFormat:@"%@%@", @"com.neal.coredata.itineraryR02.",
appDelegate.destinationPreference],
NSPersistentStoreUbiquitousContentNameKey,
persistentStoreUbiquitousContentURL,
NSPersistentStoreUbiquitousContentURLKey, [NSNumber
numberWithBool:YES],
NSMigratePersistentStoresAutomaticallyOption, [NSNumber
numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
nil];
...
42
42

43. iOS7 / OSX9
Improvements
Many unhappy campers a year ago...
• API forced synchronous sync (slow...)
• Apple didn’t realize how many people switched their
iCloud account info on-the-fly
•
And taking that into consideration was a Royal PITA for us
there wasn’t a consistent paradigm
• Apple admitted frameworks did it, we’d all be happier
realized if the
•
Apple rearchitected iCloud / Core Data integration
• Great WWDC2013 preso code (!)
but no downloadable sample
•
Good source of downloadable sample code
http://ossh.com.au/design-and-technology/software-development/sample-library-styleios-core-data-app-with-icloud-integration/
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43

44. iOS7/OSX9 Changes
Fallback Store improvements
• Entirely managed by CoreData
store file
• Only onebe stored inper iCloud account
Must
local storage
•
•
•
preferably App Sandbox
Storing “Local store” in the cloud as a document is now
discouraged
• Auto synched with cloud to ensure a local persistent
store exists while you are offline
• Events logged to console
Core Data: Ubiquity: peerID:StoreName - Using local storage: 1
44
44

45. iOS7/OSX9 Changes
Asynchronous Setup
• New notifications
these:
•
NSPersistentStoreCoordinatorStoresWillChangeNotification
NSPersistentStoreCoordinatorStoresDidChangeNotification
• encourage you to:
-[NSManagedObjectContext save:]
-[NSManagedObjectContext reset:]
• this:
• encourages you to:
NSPersistentStoreDidImportUbiquitousContentChangesNotification
-[NSManagedObjectContext mergeChangesFromContextDidSaveNotification:]
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45

46. iOS7/OSX9 Changes
Handling Account Changes
notifications:
• Oldthis:
•
• would require you to (and handle all cases of):
NSUbiquityIdentityTokenDidChangeNotification
-[NSManagedObjectContext reset:]
-[NSPersistentStoreCoordinator removePersistentStore:]
-[NSPersistentStoreCoordinator addPersistentStore:]
• New (iOS7/OSX9):
this: (look familiar?)
•
• encourages you to:
NSPersistentStoreCoordinatorStoresWillChangeNotification
-[NSManagedObjectContext save:]
-[NSManagedObjectContext reset:]
• which then: (look familiar?)
• encourages you to:
NSPersistentStoreCoordinatorStoresDidChangeNotification
-[NSManagedObjectContext save:]
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46

47. iCloud Accounts and
Stores
Provide store URL inside App Sandbox
• NOT in cloud
CoreData creates an opaque container
Each iCloud account is tied to a single local store
Store is automatically removed by CoreData when no
longer needed
See WWDC2013s207 for more details on API
• and sample code here
47
47

48. iCloud Debugging
Test with multiple devices
Xcode5 improvements
iOS simulator improvements
• iCloud Document Storage
• iCloud Key-Value Store
• Push Notifications
Core Data Logging
• NSUserDefaults
• com.apple.coredata.ubiquity.logLevel 3
com.apple.CoreData.SQLDebug 1
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48

49. iCloud Debugging
iCloud Logging
• OSX
ubcontrol -k 7
• iOS
• iCloud Debug Provisioning Profile
• from developer.apple.com/downloads
• Sync with iTunes to get logs
~/Library/Logs/CrashReporter/MobileDevice/device-name/DiagnosticLogs
Monitor Network Traffic
• Wireshark
Use airplane mode to induce conflicts
Configuration Profile
developer.icloud.com
49
49

50. iCloud Summary
It’s Ubiquitous!
iCloud Design Guide
• http://developer.apple.com/library/ios/
documentation/General/Conceptual/
iCloudDesignGuide/iCloudDesignGuide.pdf
WWDC videos
• Still watch 2012 videos to get background for iOS5/6
compatibility
• WWDC2013s207 also discusses changes to SQLite
interfacing
Caveats
•
•
•
•
Not cross-platform
Bad taste in people’s mouths from 2012-2013
Learning Curve
CoreData is NOT the same as a database
50
50

51. CoreData:
Connecting to the Cloud
an Improvement
Scott M. Neal
smn@automationgarden.com
smn.mg@acmefoo.org
scottmneal@gmail.com
© 2012-2014 AutomationGarden
51

52. Web Services
52
52

53. Types of Web Services
Message-Oriented
(aka “Big web services”)
•
• UDDI (Universal Description Discovery and Integration)
(Web Services
• WSDL(Simple ObjectDescription Language)
Access Protocol)
• SOAP
• “Chatty”--low signal/noise ratio
Resource-based
State Transfer)-HTTP
• usually REST (REpresentationalResource
Return a Representation of the
•
•
•
•
XML
JSON
?
Request
st
Reque
Web
Server
Response
Web
Service
nse
Respo
53
53

54. Resource-Based Web
Services
A URL resource request:
• scheme://domain:port/path?querystring#fragment_id
• scheme: http, https, etc.
• use https for secure requests
• domain: hostname or IP
• port (optional, scheme-dependent)
• path
• queryString
• fragment_id (rare in resource requests)
Example:
• http://maps.googleapis.com/maps/api/geocode/
json?sensor=false&address=17 SE 3rd Avenue,
Portland, OR 97214
54
54

55. Resource-Based Web
Services in iOS
Resource representation can come back as XML or
JSON
• iOS is fluent in both
We’ll start with a synchronously-loaded XML example
• RoadTrip 2
We can then look at an asynchronous version
• RoadTrip 3
Exercises “for the reader” that we don’t address here
• JSON parse (instead of XML)
• Creating your own web services
55
55

56. Road Trip 2
We create a WSManager class and use synchronous
URL to get XML and then parse it
• See addLocation:...
which calls geocodeSynchronouslyXML
•
56
56

57. Road Trip 3
Asynchronous URL connection requires a delegate and
support of the following delegate methods
• Specified in Protocol NSURLConnectionDelegate
primary
•
• connection:didReceiveResponse:
• connection:didReceiveData:
• connection:didFailWithError:
• connectionDidFinishLoading:
• optional
• connection:willCacheResponse:
• connection:willSendRequest:redirectResponse:
• connection:didReceiveAuthenticationChallenge:
• connection:didCancelAuthenticationChallenge:
• See addLocation:...
which calls geocodeAsynchronouslyXML
•
57
57