1. Writing Mobile
Applications with
Couchbase
Knoxville Cocoaheads
March 2016

2. Who is this guy?
• Mike Hagedorn
• Language Polyglot

3. Why Couchbase?
Changing face of IT Demands
HA
Scalable
Agile, Schemaless
CB: Synching, Admin GUI, SDKs

4. Couchbase History

5. Couchbase Terms
• Node
• Cluster
• Bucket
• Document
• View

6. Couchbase Components
Mobile embedded local db with sync
Gw internet facing component
Server: Ent grade nosql db

7. Couchbase Server

8. Couchbase Lite
Couchbase Lite is an embedded JSON database
that can work standalone, in a P2P network, or as a
remote endpoint for Couchbase Server.
Embedded
All IO is local
Syncs are transparent in background
Disconnected operation
NO PUSH
NO Network
CBL
Device 1
CBL
Device 2
CB
Server
Cluster 1
with
GW!

9. Sync Gateway
CBL
Device 1
CBL
Device 2
CB
Server
Cluster 1
Data
Needed
Here!
?
Remote Data Center
SGW

10. Couchbase Model
• An object oriented wrapper on top of
CBLDocument
• Somewhat like NSManagedObject

11. Couchbase Challenges
• Complicated Queries are Hard
• Views!

12. Getting Started
• DL Couchbase Lite Framework
• Add CouchbaseLite.framework to your project
• There is no step 3

13. Initialization
//AppDelegate
CBLManager *manager = [CBLManager sharedInstance];
NSError *error;
self.database = [manager databaseNamed:kDBName error: &error];
if (error) {
NSLog(@"error getting database %@",error);
exit(-1);
}

14. Database
Rockets
Name Weight Diameter Cd
alpha 29 25 0.75
hawk 35 30 0.8

15. Document
{
"coefficientFriction": 0.75,
"diameter": 25,
"name": "alpha110",
"type": "rocket",
"weight": 23
}
# Bb6YvfoCH7NIgsVDtgjE7O
Unique ID
May contain binary attachments

16. Database View
//RootController or CBModel
//Define a view that only returns documents of type ‘kRocketDocType’
CBLView* view = [db viewNamed: @"rockets"];
if (!view.mapBlock) {
// Register the map function, the first time we access the view:
[view setMapBlock: MAPBLOCK({
if ([doc[@"type"] isEqualToString:kRocketDocType])
emit(doc[@"name"], nil);
}) reduceBlock: nil version: @"1"];
}
Map/Reduce
Called on every document
Optional Reduce

17. Using Views in your UI
// Create a query showing rockets:
CBLLiveQuery* query = [[[database viewNamed:@"rockets"] query] asLiveQuery];
// Plug the query into the CBLUITableSource, which will use it to drive the table.
// (The CBLUITableSource uses KVO to observe the query's .rows
self.dataSource.query = query;
self.dataSource.labelProperty = @"name";
// Assumes something like this in your controller
@property (nonatomic) IBOutlet UITableView* tableView;
@property (nonatomic) IBOutlet CBLUITableSource* dataSource;

18. Customizing Table Cells
- (void)couchTableSource:(CBLUITableSource*)source
willUseCell:(UITableViewCell*)cell
forRow:(CBLQueryRow*)row
// Set the cell background and font:
// Configure the cell contents. Map function (above) copies the doc
properties into its value, so we can read them without having to load the
document.
NSDictionary* rowValue = row.value;
BOOL checked = [rowValue[@"check"] boolValue];
if (checked) {
cell.textLabel.textColor = [UIColor grayColor];
cell.imageView.image = [UIImage imageNamed:@"checked"];
} else {
cell.textLabel.textColor = [UIColor blackColor];
cell.imageView.image = [UIImage imageNamed: @"unchecked"];
}
// cell.textLabel.text is already set, thanks to setting up labelProperty
}

19. Selecting A Row
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath
*)indexPath
{
NSLog(@"didSelectRowAtIndexPath");
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
CBLQueryRow *row = [self.dataSource rowAtIndex:indexPath.row];
ASDRocket* rocket = [ASDRocket modelForDocument: row.document];
// Do something with rocket…
}

20. Adding Items
- (IBAction) insertNewObject: (id)sender {
ASDRocket* rocket = [ASDRocket modelForNewDocumentInDatabase:self.database];
rocket.name=name;
rocket.weight = 23.0;
NSError* error;
if (![rocket save: &error]) {
return nil;
}
NSLog(@"Rocket Created");
}

21. Deleting Items
-(void) tableView:(UITableView*)tableView
commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
forRowAtIndexPath:(NSIndexPath *)indexPath{
if (editingStyle == UITableViewCellEditingStyleDelete){
CBLQueryRow *row = [self.dataSource rowAtIndex:indexPath.row];
ASDRocket* rocket = [ASDRocket modelForDocument: row.document];
NSError* error;
if (![rocket deleteDocument: &error]){
NSLog(@"Unable to delete Rocket");
return;
}
[self.tableView reloadData];
}
}

22. Replications
CBLReplication *pull;
CBLReplication *push;
h;
pull = [_database createPullReplication:_remoteURL];
pull.continuous = YES;
pull.network = @"WiFi";
push = [_database createPushReplication:_remoteURL];
push.continuous = YES;
pull.network = @"WiFi";
[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(replicationProgress:)
name:kCBLReplicationChangeNotification
push];
[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(replicationProgress:)
name:kCBLReplicationChangeNotification
pull];

23. CBLModel
• Maps Objects to documents
@interface ASDRocket : CBLModel
+ (NSString*) docType;
@property (strong) NSString *name;
@property (assign) double diameter;
@property (assign) double weight;
@property (assign) double coefficientFriction;
/** Returns a query for all the rockets in a database. */
+ (CBLQuery*) queryRocketsInDatabase: (CBLDatabase*)db;
/** Returns a query for all the rockets with name in a database */
+ (CBLQuery*) findInDatabase:(CBLDatabase*)db byName:(NSString *)name;
@end

24. CBLModel
• No types in documents
• convention is to use type field
• Map functions can pick out docs with the right type
if (doc.type == “rocket”){
emit(doc.created, doc.text)
};

25. Demo
• https://github.com/mwhagedorn/
couchbase_ios_rockettown
• https://github.com/mwhagedorn/
couchbase_osx_rockettown
• Two platforms synching to one database

26. Questions?
• @mwhagedorn