Using amazon AWS SNS service IOS - ios

Question

I am developing an app which uses amazon aws service and it is a messenger.
I would like to use IOS Push Notification service and the amazon SNS to achieve the communication between 2 users. I am able to send message from the SNS console by publishing a message to the destination called endpoint.
However, i am not able to send message from one mobile to another mobile by amazon SDK of IOS. Can i do it in that way by the API of Amazon?
I want to send the NSDictionary called messageDict to the destination endPoint. Can i achieve this without the use of server??
NSDictionary *messageDict = [[NSDictionary alloc]init];
messageDict = #{ #"Name" : #"HelloWrold" ,#"Id" :#"GoodBye",};
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:messageDict options:NSJSONWritingPrettyPrinted error:nil];
NSString *jsonString = [[NSString alloc]initWithData:jsonData encoding:NSUTF8StringEncoding];
NSLog(#"Jsonstring %#",jsonString);
AWSSNS *publishCall = [AWSSNS new];
AWSSNSPublishInput *message = [AWSSNSPublishInput new];
message.subject = #"My First Message";
//This is the ending point
message.topicArn = #"arn:aws:sns:us-east-1:012345678912:endpoint/APNS_SANDBOX/appTesting/201sjad-XXXX-XXXX-XXXX-c34sdfdsf1d9c";
message.messageAttributes = messageDict;
message.messageStructure = jsonString;
[[publishCall publish:message]continueWithExecutor:[BFExecutor mainThreadExecutor] withBlock:^id(BFTask *task){
if (task.error != nil) {
NSLog(#"Error %#",task.error);
}
else{
NSLog(#"Successful");
}
return nil;
}];

Answer 1

The hardest thing about sending an APN with SNS is getting the data structure correct. Here is how you you can publish to a topic using swift. Each platform needs to be an encoded string, if you mess this up SNS will only deliver your default message.
func publishPush() {
let sns = AWSSNS.defaultSNS()
let request = AWSSNSPublishInput()
request.messageStructure = "json"
var aps: NSMutableDictionary = NSMutableDictionary()
var dict = ["default": "The default message", "APNS_SANDBOX": "{\"aps\":{\"alert\": \"YOUR_MESSAGE\",\"sound\":\"default\", \"badge\":\"1\"} }"]
let jsonData = NSJSONSerialization.dataWithJSONObject(dict, options: nil, error: nil)
request.message = NSString(data: jsonData!, encoding: NSUTF8StringEncoding) as! String
request.targetArn = "blahblahblah:MyTopic"
sns.publish(request).continueWithBlock { (task) -> AnyObject! in
println("error \(task.error), result:; \(task.result)")
return nil
}
}

Answer 2

You can either send a push notification to a specific device (endpoint) or to a topic (list of multiple subscribers)
The API call is slightly different for both. Either you use message.topicArn or message.targetArn as describe in the API documentation here
http://docs.aws.amazon.com/sns/latest/api/API_Publish.html
(Objective-C class documentation is here : http://docs.aws.amazon.com/AWSiOSSDK/latest/Classes/AWSSNSPublishInput.html)
Your ARN is an Endpoint ARN and your code assigns it to message.topicArn
I would change it to
message.targetArn = #"arn:aws:sns:us-east-1:123456789012:endpoint/APNS_SANDBOX/appTesting/201sjad-XXXX-XXXXXX-XXXX-c34sdfdsf1d9c";
(ARN edited to obfuscate your Account ID)
Also, please read and apply best practice from http://mobile.awsblog.com/post/Tx223MJB0XKV9RU/Mobile-token-management-with-Amazon-SNS to acquire and manage your device token.
Here is a code sample in Javascript, that you easily adapt to Objective-C.
var DEFAULT_SNS_REGION = 'eu-west-1';
var SNS_ENDPOINT_ARN = 'arn:aws:sns:eu-west-1:0123456789012:endpoint/APNS_SANDBOX/AmazonSNSPushDemo/95084b8f-XXXX-XXXX-XXXX-b3429d0fa528';
var SNS_TOPIC_ARN = 'arn:aws:sns:eu-west-1:012345678912:PushNotifications';
function sendNotification(msg, topicARN, endPointARN) {
var sns = new aws.SNS({
apiVersion: '2010-03-31',
region: DEFAULT_SNS_REGION
});
var params = {}
if (topicARN != '') {
params = {
Message: msg,
//MessageStructure: 'json',
TopicArn: topicARN
};
} else {
params = {
Message: msg,
//MessageStructure: 'json',
TargetArn: endPointARN
};
}
console.log(params);
var deferred = Q.defer();
sns.publish(params, function(err,data) {
if (err) {
console.log(err, err.stack); // an error occurred
deferred.reject(err);
} else {
console.log(data); // successful response
deferred.resolve(data);
}
});
return deferred.promise; }

Answer 3

The AWSSNS instance is not correctly instantiated.
AWSSNS *publishCall = [AWSSNS new];
needs to be changed to
AWSSNS *publishCall = [AWSSNS defaultSNS];
In general, however, I do not recommend sending push notifications from the client devices because anyone can grab the temporary credentials from the mobile device and spam your app users. Amazon SNS currently does not support fine-grain access control nor throttling the excessive send requests.
The better solution from the security point of view is to have a push notification server. You can take a look at some of the services that may help:
AWS Lambda
AWS Elastic Beanstalk