AFNetworking 2.0 : Cannot POST with JSON from IOS - ios

Question

Ever since upgrading my IOS code to use AFNetworking version 2.0 instead of 1.x, I cannot do an HTTP Post any more with JSON parameters.
I suspect it is because my HTTP request header is not "application/json" but I have tried to do that and it still does not work.
This is my test code for trying to POST by JSON:
NSDictionary *parameters = [NSDictionary dictionaryWithObjectsAndKeys:
email, #"email",
password, #"password",
nil];
[[OTApiClient sharedInstance] POST:#"login" parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"result: %#", responseObject);
Boolean response = [[responseObject valueForKey:#"success"] boolValue];
if(response == TRUE) {
//ok, success
NSLog(#"success");
UIAlertView * alert = [[UIAlertView alloc] initWithTitle:#"Success!" message:#"Successfully logged in" delegate:nil cancelButtonTitle:#"Ok" otherButtonTitles:nil];
[alert show];
} else {
NSLog(#"Not successful");
UIAlertView * alert = [[UIAlertView alloc] initWithTitle:#"Sorry" message:#"The email or password is incorrect." delegate:nil cancelButtonTitle:#"Ok" otherButtonTitles:nil];
[alert show];
}
dispatch_async(dispatch_get_main_queue(), ^{
[MBProgressHUD hideHUDForView:self.view animated:YES];
});
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"error: %# , for operation: %#", error, operation);
UIAlertView * alert = [[UIAlertView alloc] initWithTitle:#"Sorry" message:#"There is a problem connecting to the server, please try again soon." delegate:nil cancelButtonTitle:#"Ok" otherButtonTitles:nil];
[alert show];
dispatch_async(dispatch_get_main_queue(), ^{
[MBProgressHUD hideHUDForView:self.view animated:YES];
});
}];
});
and I keep getting this error :
Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=0xca80730 {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.} , for operation: <AFHTTPRequestOperation: 0xca6bee0, state: isFinished, cancelled: NO request: <NSMutableURLRequest: 0xca76040> { URL: http://1.2.3.4:9000/api/login }, response: <NSHTTPURLResponse: 0xc963d60> { URL: http://1.2.3.4:9000/error404 } { status code: 404, headers {
"Content-Length" = 1809;
"Content-Type" = "text/html; charset=utf-8";
} }>
I am very sure that the server is up and accessible because all other GET calls work properly.
I have checked the updated documentation for AFNetworking 2.0 and it seems like what I have is the right way to do a JSON POST
Please let me know if I missed anything
Thanks
IS

Answer 1

Actually, I finally got it to work.
Basically, for my requestSerializer of the AFHTTPRequestOperationManager, I was using AFHTTPRequestSerializer and then trying to set the Content-Type to "application/json"
But once I switched to using AFJSONRequestSerializer instead, it works fine now
AFJSONRequestSerializer *requestSerializer = [AFJSONRequestSerializer serializer];
[requestSerializer setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[requestSerializer setValue:#"application/json" forHTTPHeaderField:#"Accept"];
operationManagerInstance.requestSerializer = requestSerializer;

Answer 2

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
AFJSONRequestSerializer *serializer = [AFJSONRequestSerializer serializer];
[serializer setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[serializer setValue:#"application/json" forHTTPHeaderField:#"Accept"];
manager.requestSerializer = serializer;
now it will work.

Answer 3

I encountered the same problem using AFNetworking API through Swift, trying to send a post request and finally got it work as well thanks to user1805458's post.
Basically, for my requestSerializer of the AFHTTPRequestOperationManager, I was also using AFHTTPRequestSerializer and then trying to set the Content-Type to "Application/JSON" and it did not work.
But once I switched to using AFJSONRequestSerializer instead, it works fine now:
let manager = AFHTTPRequestOperationManager()
manager.requestSerializer = AFJSONRequestSerializer(writingOptions: nil)
// Contrary to user1805458's solution, I did not need to use these two instructions below using Swift.
// manager.requestSerializer.setValue("Application/JSON", forHTTPHeaderField:"Content-Type")
// manager.requestSerializer.setValue("Application/JSON", forHTTPHeaderField:"Accept")
I hope it will help you to fix this error in case where you use Swift, AFNetworking and try to send a post request containing a JSON body.