You can use the STTwitter library which makes all of this very very easy:
self.twitter = [STTwitterAPI twitterAPIOSWithFirstAccount];
[_twitter verifyCredentialsWithSuccessBlock:^(NSString *username) {
[_twitter getFollowersForScreenName:username successBlock:^(NSArray *followers) {
NSLog(@"-- %@", followers);
} errorBlock:^(NSError *error) {
//
}];
} errorBlock:^(NSError *error) {
//
}];