Simple sample of In-App purchase receipt verification and storage in Mobile Services DB

insert.receipts.js

// This server script 'swizzles' the data. It takes an item that will NOT be inserted to the database. 
// Instead the item.receipt property is forwarded to the App Store to verify the receipt is valid. If so,
// Apple will return a full receipt with many properties including the purchase time, product Id etc. 
// Instead then, we insert this data to the database along with the userId so we know who made the purchase.
var req = require('request');
var table = tables.getTable('receipts');

function insert(item, user, request) {
    req.post({
        // change this to buy.itunes.apple.com for production
        url: 'https://sandbox.itunes.apple.com/verifyReceipt',
        body: JSON.stringify({ "receipt-data" : new Buffer(item.receipt).toString('base64') })   
    }, function(e, r, body) {
        if (r.statusCode !== 200) {
            console.error(r);
            request.respond(400, "Failed to verify receipt");
        }
        else {
            var data = JSON.parse(body);
            if (data.status === 0) {
                // we're good. Insert the receipt to the DB
                data.receipt.userId = user.userId;
                table.insert(data.receipt, {
                    success: function() {
                        request.respond(200, data.receipt);
                    }
                })
            }
            else {
                console.error(r);
                request.respond(500, { status: data.status, error: "receipt validation failed" });
            }
        }
    });
}

TodoService.m

// this is from the client code - simply pass the transactionReceipt property of the SKPaymentTransaction
// as the receipt parameter to the method below. This will POST the data to the mobile service which will,
// in turn, invoke the insert function on the server shown in this gist
- (void)insertReceipt:(NSData *)receipt completion:(CompletionBlock)completion
{
    NSString *string = [[NSString alloc] initWithData:receipt encoding:NSUTF8StringEncoding];
    [self.receipts insert:@{ @"receipt" : string } completion:^(NSDictionary *item, NSError *error) {
        completion();
    }];
}