Way too many apps on the App Store totally break when you loose connectivity. Have a look at some study cases and hopefully by the end you will figure out that implementing offline mode in your app is not that difficult at all.

1. Offline Mode
Overcome your fear of implementing
in your apps
www.addofflinemode.com

2. Offline Mode
Overcome your fear of implementing
in your apps
www.addofflinemode.com

3. Marin Todorov
(me)

4. raywenderlich.com

5. Today you will
See common offline mode fails and wins
Draw a lot of good advice in the process
Finally have a look at few tools

6. Connected apps
web services

7. Internet in your pocket

8. Web services in the cloud
Photo credit: Flickr, Torkild RetvedtPhoto credit: Flickr, Tim Bates

9. …
Photo credit: Flickr, Torkild RetvedtPhoto credit: Flickr, Marcin Kargol

10. Oops (no connection)

11. Maybe?

12. Ehm?

13. offline gprs/edge

14. Awesome :)

15. Awesome :)

16. - offline
- bad connectivity
- online
3 modes

17. - offline
3 modes

18. - bad connectivity
3 modes
CTTelephonyNetworkInfo currentRadioAccessTechnology
CTRadioAccessTechnologyGPRS
CTRadioAccessTechnologyEdge
CTRadioAccessTechnologyLTE
CTRadioAccessTechnologyDidChangeNotification

19. - online
3 modes
current step
steps top pre-fetch

20. - rely on what makes sense
UI wise

21. How to handle offline
mode

22. There is no universal solution

23. THE END

24. - asses the problem
- evaluate the solution
- code
3 steps
in this order please!

25. Klout

26. Klout
NSUserDefaults
name
score
4 last updates
2 last connections
JSON

27. Klout
Online?
Start
Fetch JSON
UI Code
Done
Start
Fetch JSON
UI Code
Done
Local JSON
Store locally
YESNO

28. Simple solution for a simple problem
First asses, then evaluate, then code

29. York cinemas

30. York cinemas

31. cinemas in Berlin - these change once a year
!
film schedule changes every thursday
!
static information - practically doesn’t change
!
ticket reservations
Photo credit: Flickr, Tobias Abel Photo credit: Flickr, InSapphoWeTrust

32. 12 cinema photos + their names + coordinates
25 film posters + film names
30 movie times for all cinemas
!
7KB sqlite file
2MB of photos
!
=
!
< 1 Facebook photo in size

33. 20.03 Thu Sat 27.03 Thu

34. Check this out York cinemas!
This
week?
Start
Read sqlite database
UI Code
Done
Start
Fetch 1 file
UI Code
Done
YES
NO
Read sqlite database

35. The problem definition contained the solution
Sqlite database is a single file
You don’t need past data

36. How about ticket reservations?

37. You got to to some things online!

38. You can still do SOMETHING

39. A stock trading app
price changes all the time
!
displays historical data
!
allows for real-time buying/selling

40. price changes all the time
!
displays historical data
!
allows for real-time buying/selling
Past data does not change…

41. 14:40 14:50 15:00
14:30 14:40 14:50

42. 14:40 14:50 15:00
Time on plane

43. 14:50 15:00
Time on plane
BUY
3 hrs

44. For long lists - use sqlite
AAPL!
123456 11.6 10.5
123459 11.5 10.5
123460 12.0 11.0
123470 14.0 11.5
123490 14.0 10.5
Easy to sync to local database
server database JSON local sqlite
AAPL!
!
!
!
123470 14.0 11.5
123490 14.0 10.5
aapl
keep ids from the server

45. How to fetch the delta data?
14:40 14:50 15:00
+ tokenA + tokenB + tokenC
+ tokenA + tokenB

46. Facebook
posts come in all the time
!
posting in not time crucial
!
chat with friends
!
location check-in

47. 14:40 14:50 13:20
Time on plane

49. 14:40 14:50 13:20
Time on plane
OMG! Great flight
attendants on the
flight to Lisbon!

52. Core Data = power + pain
You need to recreate the relationships
Migration strategy

53. What’s the foreseeable outcome of the create/edit
operations?
Data validation
Cache the create operation data

54. 3 ways to store temporary objects
!
1. create the new objects, store them using NSCoding
2. create a separate store for pending objects
3. use existing store, but use ids < 0

55. How to change your app
architecture

56. cloud
Network layer
REST
JSON RPC
JSON API
XML? plist?
Connectivity
User Interface
data storage
NSCoding
sqlite3
Core Data
Cache
file system
Core Data
file storage
You probably have this setup

57. cloud
Network layer
REST
JSON RPC
JSON API
XML? plist?
Connectivity
User Interface
data storage
NSCoding
sqlite3
Core Data
Cache
file system
Core Data
file storage
You want to have this setup

58. Prefer reading from local source,
update local source from Internet

59. Power tools
network, storage, UI …

60. sorry, iPhone only

61. CoreTelephony.framework
CTTelephonyNetworkInfo -> currentRadioAccessTechnology
!
CTTelephonyNetworkInfo -> subscriberCellularProvider.isoCountryCode
!

62. NSURLSession
NSURLSession
CloudCode Cookie policy
Auth policy
Caching policy
Storing files
Timeouts
etc. etc.

63. NSURLSessionConfiguration

64. Reachability
https://github.com/tonymillion/Reachability
!
arc, gdc, ios/osx, maximum wins
reach
=
[Reachability
reachabilityWithHostname:@"www.addofflinemode.com"];
reach.unreachableBlock
=
^(Reachability*reach)
{
NSLog(@"UNREACHABLE!");
};

65. JSONModel
https://github.com/icanzilb/JSONModel
!
model classes, validation, data conversion, etc.

66. JSONModel
{“id”:1, “name”:”Marin”}
NSNumber* id;
NSString* name;
NSManagedObject
Model
JSON

67. Core Data
NSFetchedResultsController
!
Core Data Editor
Image: http://thermal-core.com/CoreDataEditor/

68. Core Data
TBCoreDataStore!
!
http://robots.thoughtbot.com/core-data
Main Queue!
context
Background Queue!
context read
write
merge
Internet!
JSON

69. FMDB
https://github.com/ccgus/fmdb
!
Objc sqlite made easy
FMResultSet
*s
=
[db
executeQuery:@"SELECT
*
FROM
myTable"];
while
([s
next])
{
//retrieve
values
for
each
record
}

70. NSCoding
NSData* encodedData = [NSKeyedArchiver archivedDataWithRootObject: myObject];
[encodedData writeToURL:localFileURL atomically:YES];

71. Cache
simpler cache library - EGOCache
https://github.com/enormego/EGOCache
image caching - FastImageCache
https://github.com/path/FastImageCache
[[EGOCache globalCache] setObject:JSONResponse forKey:@"cachedJSON"];
[[EGOCache globalCache] setImage:myImage forKey:@"photo"
withTimeoutInterval:60*60];

72. Sequencer
https://github.com/berzniz/Sequencer
!
async flow control
Get X Post Y Location Update UI
[sequencer enqueueStep:^(id result, SequencerCompletion completion) {
[self testSectionUnloggedGets: nil];
completion(nil);
}];
!
[sequencer enqueueStep:^(id result, SequencerCompletion completion) {
[self postToServer: ^{
completion(nil);
}];
}];

73. What’s next?

74. Turn on plane mode and check how your
favorite apps look like
Check how your app looks like (eeek!)
Get in touch, discuss, check out the power-tools

75. That’s all folks

76. Offline Mode
Overcome your fear of implementing
in your apps
www.addofflinemode.com