Linkedin ios sdk returns wrong data - ios

Question

I have integrated linkedin ios sdk in my ios app. So when I click on button to authenticate with linkedin a viewcontroller is shown and page to enter username and password is shown. Now when I enter the correct username and password it returns a url with code and state in it. The problem is that the state(which is a random string) which was send with the request is not the same that is received in response url. For example if I send
state = #"qwertyu"
Then the return value is
state = #"qwertyu#!"
An extra #! is appended with it.
In the code I am checking if the send and received state are same as it is not same I am returning an error(This is the error which it shows after entering correct username and password). If I remove that if condition then it is working perfectly fine.
SYLinkedInApplication *app = [SYLinkedInApplication
applicationWithRedirectURL:self.redirectUrl
clientId:self.appKey
clientSecret:self.appSecret
state:#"<RANDOM-STRING>"
grantedAccess:#[#something];
The condition
if ([self.application.state isEqualToString:receivedState]) {
//if true send success
}
So my question is
1) Do we need the if condition for checking the state?
2) If we need the condition then why is the return state string different?
Hope the question is clear.
Thanks in advance.

Answer 1

I solved the problem (but with Ionic).
1) Yes you should check for the state, to prevent CSRF.
2) That's the problem I solved by changing the URL when requesting authorization and access token:
From https://www.linkedin.com/uas/oauth2/authorization to https://www.linkedin.com/oauth/v2/authorization
And https://www.linkedin.com/uas/oauth2/accessToken to https://www.linkedin.com/oauth/v2/accessToken
That solved my problem. I hope it solves yours too, or someone else's.