If enable the facebook account in settings, when change account can't open the session.
-(void)fbResync
{
ACAccountStore *accountStore;
ACAccountType *accountTypeFB;
if ((accountStore = [[ACAccountStore alloc] init]) && (accountTypeFB = [accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierFacebook] ) ){
NSArray *fbAccounts = [accountStore accountsWithAccountType:accountTypeFB];
id account;
if (fbAccounts && [fbAccounts count] > 0 && (account = [fbAccounts objectAtIndex:0])){
[accountStore renewCredentialsForAccount:account completion:^(ACAccountCredentialRenewResult renewResult, NSError *error) {
//we don't actually need to inspect renewResult or error.
if (error){
}
}];
}
}
[FBSession openActiveSessionWithReadPermissions:permissions
allowLoginUI:YES
completionHandler:^(FBSession *session, FBSessionState state, NSError *error) {
if(error)
{
NSLog(@"Session error");
[self fbResync];
[NSThread sleepForTimeInterval:0.5]; //half a second
[FBSession openActiveSessionWithReadPermissions:permissions
allowLoginUI:YES
completionHandler:^(FBSession *session, FBSessionState state, NSError *error) {
[self sessionStateChanged:session state:state error:error];
}];
}
else
[self sessionStateChanged:session state:state error:error];
}];