You're already there. Completion block should be:
{
bool actuallyGranted = granted;
NSArray *accounts = [accountStore accountsWithAccountType:accountType];
if (!accounts || ([accounts count] == 0))
actuallyGranted = false;
if (actuallyGranted)
{
}
else
{
}
}
A similar call for FB does not need this - value for "granted" will be correct. I'm assuming the special case needed for twitter is an iOS bug.