GeoPix: A sample iOS app powered by IBM MobileFirst for Bluemix

In this post I’d like to show a fairly simple application that I put together which shows off some of the rich capabilities for IBM MobileFirst for Bluemix that you get out of the box – All with an absolute minimal amount of your own developer effort.  Bluemix, of course, being IBM’s platform as a service offering.

GeoPix is a sample application leveraging IBM MobileFirst for Bluemix to capture data and images on a mobile device, persist that data locally (offline), and replicate that data to the cloud. Since it’s built with IBM MobileFirst, we get lots of things out of the box, including operational analytics, user authentication, and much more.

(full source code at the bottom of this post)

Here’s what the application currently does:

• User can take a picture or select an image from the device
• App captures geographic location when the image is captured
• App saves both the image and metadata to a local data store on the device.
• App uses asynchronous replication to automatically save any data in local store up to the remote store whenever the network is available
• Oh yeah, can’t forget, the user auth is via Facebook
• MobileFirst provides all the analytics we need.  Bluemix provides the cloud based server and Cloudant NoSQL data store.
• All captured data is available on a web based front-end powered by Node.js

Here’s a video of it in action:

… and you can check out the web interface at geopix.mybluemix.net.

(full source code at the bottom of this post)

This is powered by the iOS 8 MobileFirst application boilerplate on Bluemix.  With this application template you can have your backend infrastructure setup within minutes, and it includes:

• User authentication
• Usage/operational analytics
• Cloudant NoSQL DB
• Simplified Push Notifications
• Node.js backend

In this sample I’m using everything but the Push Notifications service.  I’m using user authentication, the Cloudant DB (offline/local store and remote/cloud store), and the node.js backend.  You get the operational analytics automatically.

To get started, you just need to create a new iOS 8 mobile application on Bluemix.  See my video series on Getting Started with IBM MobileFirst for Bluemix for a complete walkthrough of creating a new app using MobileFirst for Bluemix, or check out the Getting Started Guide in the official docs.

You need to initialize your app, and make sure you have setup the Facebook identity provider.  You can create your Facebook authentication at https://developers.facebook.com/.  Once the user is authenticated, the client app is fully functional.

The app UI is very simple, basically just two buttons for capturing images (the last captured image shows up in the background):

There’s also a gallery for viewing local images:

Capturing Location

Capturing data is very straightforward.  The geographic location is captured using Apple’s Core Location framework.  We just need to implement the CLLocationManagerDelegate protocol:

[objc]- (void)locationManager:(CLLocationManager *)manager
didUpdateLocations:(NSArray *)locations {

self.currentLocation = [locations lastObject];
NSDate* eventDate = self.currentLocation.timestamp;
NSTimeInterval howRecent = [eventDate timeIntervalSinceNow];
if (abs(howRecent) < 15.0) {
// If the event is recent, do something with it.
locationLabel.text = [NSString stringWithFormat:@" Lat: %+.5f, Lon: %+.5f\n",
self.currentLocation.coordinate.latitude,
self.currentLocation.coordinate.longitude];
}
}[/objc]

Then initialize CLLocationManager using our class as the location manager’s delegate:

[objc]if (self.locationManager == nil)
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.pausesLocationUpdatesAutomatically = YES;[/objc]

Capturing Images

Capturing images from the device is also very straightforward.  In the app I leverage Apple’s UIImagePickerController to allow the user to either upload an existing image or capture a new image.  See the presentImagePicker and didFinishPickingMediaWithInfo below. All of this standard practice using Apple’s developer SDK:

[objc]- (void) presentImagePicker:(UIImagePickerControllerSourceType) sourceType {
if ( sourceType == UIImagePickerControllerSourceTypeCamera && ![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
[logger logErrorWithMessages:@"device has no camera"];
UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"Device has no camera"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles: nil];
[myAlertView show];
};

if ( sourceType != UIImagePickerControllerSourceTypeCamera || [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] ){
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = NO;
picker.sourceType = sourceType;

[self presentViewController:picker animated:YES completion:NULL];
}
}

– (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

[logger logDebugWithMessages:@"didFinishPickingMediaWithInfo"];
UIImage *image = info[UIImagePickerControllerOriginalImage];
currentImage.image = image;
[[DataManager sharedInstance] saveImage:image withLocation:self.currentLocation];
[picker dismissViewControllerAnimated:YES completion:nil];
}[/objc]

Persisting Data

If you notice in the didFinishPickingMediaWithInfo method above, there is a call to the DataManager’s saveImage withLocation method. This is where we save data locally and rely on Cloudant’s replication to automatically save data from the local data store up to the Cloudant NoSQL database.  This is powered by the iOS 8 Data service from Bluemix.

The first thing that we will need to do is initialize the local and remote data stores. Below you can see my init method from my DataManager class. In this, you can see the local data store is initialized, then the remote data store is initialized. If either data store already exists, the existing store will be used, otherwise it is created.

[objc]-(id) init {
self = [super init];

if ( self ) {
logger = [IMFLogger loggerForName:NSStringFromClass([self class])];
[logger logDebugWithMessages:@"initializing local datastore ‘geopix’…"];

// initialize an instance of the IMFDataManager
self.manager = [IMFDataManager sharedInstance];

NSError *error = nil;
//create a local data store
self.datastore = [self.manager localStore:@"geopix" error:&error];

if (error) {
[logger logErrorWithMessages:@"Error creating local data store %@",error.description];
}

//create a remote data store
[self.manager remoteStore:@"geopix" completionHandler:^(CDTStore *store, NSError *error) {
if (error) {
[logger logErrorWithMessages:@"Error creating remote data store %@",error.description];
} else {
[self.manager setCurrentUserPermissions:DB_ACCESS_GROUP_MEMBERS forStoreName:@"geopix" completionHander:^(BOOL success, NSError *error) {
if (error) {
[logger logErrorWithMessages:@"Error setting permissions for user with error %@",error.description];
}

[self replicate];
}];
}
}];

//start replication
[self replicate];
}

return self;
} [/objc]

Once the data stores are created, you can see that the replicate method is invoked.  This starts up the replication process to automatically push changesfrom the local data store to the remote data store “in the cloud”.

Therefore, if you’re collecting data when the app is offline, then you have nothing to worry about.  All of the data will be stored locally and pushed up to the cloud whenever you’re back online – all with no additional effort on your part.  When using replication with the Cloudant SDK, you just have to start the replication process and let it do it’s thing… fire and forget.

In my replicate function, I setup CDTPushReplication for pushing changes to the remote data store.  You could also setup two-way replication to automatically pull new changes from the remote store.

[objc]-(void) replicate {
if ( self.replicator == nil ) {
[logger logDebugWithMessages:@"attempting replication to remote datastore…"];

__block NSError *replicationError;
CDTPushReplication *push = [self.manager pushReplicationForStore: @"geopix"];
self.replicator = [self.manager.replicatorFactory oneWay:push error:&replicationError];
if(replicationError){
// Handle error
[logger logErrorWithMessages:@"An error occurred: %@", replicationError.localizedDescription];
}

self.replicator.delegate = self;

replicationError = nil;
[logger logDebugWithMessages:@"starting replication"];
[self.replicator startWithError:&replicationError];
if(replicationError){
[logger logErrorWithMessages:@"An error occurred: %@", replicationError.localizedDescription];
}else{
[logger logDebugWithMessages:@"replication start successful"];
}
}
else {
[logger logDebugWithMessages:@"replicator already running"];
}
}[/objc]

Once we’ve setup the remote and local data stores and setup replication, we now are ready to save the data the we’re capturing within our app.

Next is my saveImage withLocation method.  Here you can see that it creates a new CDTMutableDocumentRevision object (this is a generic object for the Cloudant NoSQL database), and populates it with the location data and timestamp.   It then creates a jpg image from the UIImage (passed in from the UIImagePicker above) and adds the jpg as an attachment to the document revision.  Once the document is created, it is saved to the local data store.   We then let replication take care of persisting this data to the back end.

[objc]-(void) saveImage:(UIImage*)image withLocation:(CLLocation*)location {

[logger logDebugWithMessages:@"saveImage withLocation"];

//save in background thread
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^(void) {

[logger logDebugWithMessages:@"creating document…"];

NSDate *now = [NSDate date];
NSString *dateString = [NSDateFormatter localizedStringFromDate:now
dateStyle:NSDateFormatterShortStyle
timeStyle:NSDateFormatterFullStyle];

// Create a document
CDTMutableDocumentRevision *rev = [CDTMutableDocumentRevision revision];
rev.body = @{
@"sort": [NSNumber numberWithDouble:[now timeIntervalSince1970]],
@"clientDate": dateString,
@"latitude": [NSNumber numberWithFloat:location.coordinate.latitude],
@"longitude": [NSNumber numberWithFloat:location.coordinate.longitude],
@"altitude": [NSNumber numberWithFloat:location.altitude],
@"course": [NSNumber numberWithFloat:location.course],
@"type": @"com.geopix.entry"
};

[logger logDebugWithMessages:@"creating image attachment…"];

NSDate *date = [NSDate date];
NSString *imageName = [NSString stringWithFormat:@"image%f.jpg", [date timeIntervalSince1970]];

NSString *tempDirectory = NSTemporaryDirectory();
NSString *imagePath = [tempDirectory stringByAppendingPathComponent:imageName];

[logger logDebugWithMessages:@"saving image to temporary location: %@", imagePath];

NSData *imageData = UIImageJPEGRepresentation(image, 0.1);
[imageData writeToFile:imagePath atomically:YES];

CDTUnsavedFileAttachment *att1 = [[CDTUnsavedFileAttachment alloc]
initWithPath:imagePath
name:imageName
type:@"image/jpeg"];

rev.attachments = @{ imageName: att1 };

[self.datastore save:rev completionHandler:^(id savedObject, NSError *error) {
if(error) {
[logger logErrorWithMessages:@"Error creating document: %@", error.localizedDescription];
}
[logger logDebugWithMessages:@"Document created: %@", savedObject];
}];

[self replicate];
});
}[/objc]

If we want to query data from either the remote or local data stores, we can just use the performQuery method on the data store. Below you can see a method for retrieving data for all of the images in the local data store.

[objc]-(void) getLocalData:(void (^)(NSArray *results, NSError *error)) completionHandler {

NSPredicate *queryPredicate = [NSPredicate predicateWithFormat:@"(type = ‘com.geopix.entry’)"];
CDTCloudantQuery *query = [[CDTCloudantQuery alloc] initWithPredicate:queryPredicate];

[self.datastore performQuery:query completionHandler:^(NSArray *results, NSError *error) {

completionHandler( results, error );
}];
}[/objc]

At this point we’ve now captured an image, captured the geographic location, saved that data in our local offline store, and then use replication to save that data up to the cloud whenever it is available.

AND…

We did all of this without writing a single line of server-side logic.   Since this is built on top of MobileFirst for Bluemix, all the backend infrastructure is setup for us, and we get operational analytics to monitor everything that is happening.

With the operational analytics we get:

• App usage
• Active Devices
• Network Usage
• Authentications
• Data Storage
• Device Logs (yes, complete debug/crash logs from devices out in the field)
• Push Notification Usage

Sharing on the web

Up until this point we haven’t had to write any back-end code. However the mobile app boilerplate on Bluemix comes with a Node.js server.  We might as well take advantage of it.

I exposed the exact same data captured within the app on the Node.js service, which you can see at http://geopix.mybluemix.net/.

The Node.js back end comes preconfigured to leverage the express.js framework for building web applications.  I added the jade template engine and Leaflet for web-mapping, and was able to crank this out ridiculously quickly.

The first thing we need to do is make sure  we have our configuration variables for accessing the Cloudant service from our node app.  These are environment vars that you get automatcilly if you’re running on Bluemix, but you need to set these for your local dev environment:

[js]var credentials = {};

if (process.env.hasOwnProperty("VCAP_SERVICES")) {
// Running on Bluemix. Parse out the port and host that we’ve been assigned.
var env = JSON.parse(process.env.VCAP_SERVICES);
var host = process.env.VCAP_APP_HOST;
var port = process.env.VCAP_APP_PORT;

credentials = env[‘cloudantNoSQLDB’][0].credentials;
}
else {

//for local node.js server instance
credentials.username = "cloudant username here";
credentials.password = "cloudant password here";
credentials.url = "cloudant url here";
}[/js]

Next we’ll add our URL/content mappings:

[js]app.get(‘/’, function(req, res){
prepareData(res, ‘map’);
});

app.get(‘/list’, function(req, res){
prepareData(res, ‘list’);
});[/js]

Next you’ll se the logic for querying the Cloudant data store and preparing the data for our UI templates. You can customize this however you want – caching for performance, refactoring for abstraction, or whatever you want. All interactions with Cloudant are powered by the Cloudant Node.js Client

[js]var prepareData = function(res, template) {
var results = [];

//create the index if it doesn’t already exist
var sort_index = {name:’sort’, type:’json’, index:{fields:[‘sort’]}};
geopix.index(sort_index, function(er, response) {
if (er) {
throw er;
}

//perform the search
//we’re just pulling back all
//data captured ("sort" will be numeric)
var selector = {sort:{"$gt":0}};
geopix.find({selector:selector, sort:["sort"]}, function(er, result) {
if (er) {
throw er;
}

//prepare data for template
for (var x=0; x<result.docs.length; x++) {
var obj = result.docs[x];

for (var key in obj._attachments) {
obj.image = credentials.url + "/" + database + "/" + obj._id +"/" + key;
break;
}

results.push( obj );
}
res.render(template, { results:results});
});
});
};[/js]

After the prepareData method has prepared data for formatting in the UI, the template is rendered by invoking Jade’s render method:

[js]res.render(template, { results:results});[/js]

This will render whichever template was passed in – I have two: map.jade (the map template) and list.jade (the list template). You can check out the list template below, and see it in action here: http://geopix.mybluemix.net/list

[html]html
head
title GeoPix – powered by Bluemix
link(href=’//maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css’ rel=’stylesheet’)
link(href=’/public/css/index.css’ rel=’stylesheet’)
meta(name="viewport" content="width=device-width, initial-scale=1")
body
div(class=’well’)
h1 GeoPix – Powered by Bluemix
p
a(href=’/’) Map
&nbsp;|&nbsp;
a(href=’/list’) List
div(class="container-fluid")
each val, index in results
div(class="col-md-6")
div(class="panel panel-default")
div(class="panel-heading")
h3= val.clientDate
div(class="panel-body")
img(src=val.image)
p= ‘latitude: ‘ + val.latitude + ", longitude:" + val.longitude + ", altitude:" + val.altitude[/html]

In the map view I used the Leaflet map engine and Open Street Map data, along with the Leaflet Marker Cluster plugin for displaying clustered results.

Source Code

You can check out the web interface live at: http://geopix.mybluemix.net/.  If you want to setup the environment on your own, you can grab the complete source code at:

• (server) https://hub.jazz.net/project/andrewtrice/GeoPix
• (client) https://hub.jazz.net/project/andrewtrice/GeoPix-Client/

Helpful Links

• MobileFirst for Bluemix iOS 8 Documentation
• Advanced Mobile Access Documentation
• Cloudant/Mobile Data Documentation
• Cloudant Node.js Client
• Express.js Docs
• Leaflet Docs
• Apple CoreLocation Docs
• Apple UIImagePickerController Docs

Ready to start building your own apps on IBM Bluemix?  Just head over to http://bluemix.net and get a free developer trial today!