Create Order to Spree ecommerce using iOS app - spree

Question

In my app, i want to order a product in spree e-commerce by iPhone app. I easily get the products name and their detail but while creating order for products it's return the error in html page :
<h1>
TypeError
in Spree::Api::V1::OrdersController#create
</h1>
<pre>can't convert Symbol into Integer</pre>
I m sending post request as:
NSString *str = [NSString stringWithFormat:#"http://localhost:3000/api/orders"];
NSURL *urlForBuy = [NSURL URLWithString:[str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:urlForBuy];
NSString *idVariant = [NSString stringWithFormat:#"order[line_items][%d][variant_id]",0];
NSString *qnty = [NSString stringWithFormat:#"order[line_items][%d][quantity]",0];
NSString *idVariantValue = #"123456";
[request setPostValue:[NSString stringWithFormat:#"%d",[idVariantValue intValue]] forKey:idVariant];
[request setPostValue:[NSString stringWithFormat:#"%d",1] forKey:qnty];
[request setPostValue:#"<my admin token>" forKey:#"token"];
[request setRequestMethod:#"POST"];
[request setDelegate:self];
[request setDidFinishSelector:#selector(buyResponse:)];
[request setDidFailSelector:#selector(buyResponse_failed:)];
[networkQueue addOperation:request];
[networkQueue go];
Also, this url i get from REST api documentation of Spree which is: http://guides.spreecommerce.com/rest.html
Another thing I want to know what is [line_items] in this url... Also if their is any tutorial apart from above url?...Thanks in advance.

Answer 1

Orders are created through the API by passing in line items as shown in this test.
api_post :create, :order => {
:line_items => [
{
:variant_id => variant.to_param,
:quantity => 5
}
]
}
The line_items parameter is expected to be an array of hashes, consisting of a variant_id and a quantity field. The documentation says the request looks like this:
POST /api/orders?order[line_items][0][variant_id]=1&order[line_items[0][quantity]=5
I hope that helps you understand it better!