Sending a NSMutableURLRequest request with "Body Requests" - ios

Question

I'm currently working with YouTube API and allowing users to subscribe to other channels, however now I'm supposed to send a POST method that includes a "Request Body".
Here's the Request that's I'm supposed to send :
POST https://www.googleapis.com/youtube/v3/subscriptions?part=snippet&key={YOUR_API_KEY}
//The Request Body
{
"snippet": {
"resourceId": {
"channelId": "UCJZ7f6NQzGKZnFXzFW9y9UQ"
}
}
}
Here's my current code
+(void)subscribeToChannel:(NSString *)channelID {
GTMOAuth2Authentication *auth;
auth = [GTMOAuth2ViewControllerTouch authForGoogleFromKeychainForName:kKeychainItemName clientID:clientIDclientSecret:clientSecret];
NSString *urlStr;
NSMutableURLRequest *request;
urlStr = [NSString stringWithFormat:#"https://www.googleapis.com/youtube/v3/subscriptions?id=%#&key=mykey", channelID];
[request setHTTPBody:[#"{ \"snippet\": { \"resourceId\": { \"channelId\": \"UCJZ7f6NQzGKZnFXzFW9y9UQ\" } } }" dataUsingEncoding:NSUTF8StringEncoding]];
NSURL *url = [NSURL URLWithString:urlStr];
request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:#"POST"];
[auth authorizeRequest:request
completionHandler:^(NSError *error) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,
(unsigned long)NULL), ^(void) {
NSString *output = nil;
if (error) {
output = [error description];
NSLog(#"ERRO LOADING INFO : %#", output);
} else {
NSURLResponse *response = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:request
returningResponse:&response
error:nil];
if (data) {
output = [[NSString alloc] initWithData:data
encoding:NSUTF8StringEncoding];
} else {
output = [error description];
}
}
});
}];
}
I'm positive that I'm doing something wrong in [request setHTTPBody] but that's the only thing that I could think about.

Answer 1

You're attempting to set the NSMutableURLRequest's HTTPBody before you have allocated an instance of NSMutableURLRequest.
NSString *urlStr;
// The request is nil
NSMutableURLRequest *request;
urlStr = [NSString stringWithFormat:#"https://www.googleapis.com/youtube/v3/subscriptions?id=%#&key=mykey", channelID];
// At this point the request is still nil so you are attempting to set the HTTPBody on a nil object
[request setHTTPBody:[#"{ \"snippet\": { \"resourceId\": { \"channelId\": \"UCJZ7f6NQzGKZnFXzFW9y9UQ\" } } }" dataUsingEncoding:NSUTF8StringEncoding]]
You also mentioned in a comment that you are receiving a "This API does not support parsing form-encoded input." error. You may be receiving this error because you are not setting the content-type (I came to this conclusion from googling the error. I may be wrong).
This should work:
NSString * urlStr = [NSString stringWithFormat:#"https://www.googleapis.com/youtube/v3/subscriptions?id=%#&key=mykey", channelID];
NSURL *url = [NSURL URLWithString:urlStr];
NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:#"POST"];
// Set the content type
[request setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
// Create the dictionary that you will be using in the HTTPBody
NSDictionary * httpBody = #{
#"snippet": #{
#"resourceId": #{
#"channelId": channelID
}
}
};
// Make sure that the above dictionary can be converted to JSON data
if([NSJSONSerialization isValidJSONObject:httpBody])
{
// Convert the JSON object to NSData
NSData * httpBodyData = [NSJSONSerialization dataWithJSONObject:httpBody options:0 error:nil];
// set the http body
[request setHTTPBody:httpBodyData];
}
I do this when bumping places using the Google Places API, but it should work the same.

Answer 2

Try this:-
NSMutableDictionary *channelId = [[NSMutableDictionary alloc]init];
[channelId setObject:#"UCJZ7f6NQzGKZnFXzFW9y9UQ" forKey:#"channelId"];
NSMutableDictionary *resourceId = [[NSMutableDictionary alloc]init];
[resourceId setObject:channelId forKey:#"resourceId"];
NSDictionary * postDictionary = [NSDictionary dictionaryWithObject:resourceId forKey:#"snippet"];
NSError * error = nil;
NSData * jsonData = [NSJSONSerialization dataWithJSONObject:postDictionary options:NSJSONWritingPrettyPrinted error:&error];
[request setHTTPBody:jsonData];