iOS [__NSCFString > objectForKeyedSubscript:]: - ios

Question

I am trying to implement a tableview with a twitter feed into my iOS app. I have followed tutorials and am able to get the users twitter feed. I found the url for a hash tag but when implemented get an error:
'NSInvalidArgumentException', reason: '-[__NSCFString
objectForKeyedSubscript:]: unrecognized selector sent to instance
0xa0b7e20'
I have tried to do some research but all attempts failed. Any advice would be great. Thank you.
.h
#import <UIKit/UIKit.h>
#import <Social/Social.h>
#import <Accounts/Accounts.h>
#interface ViewController : UIViewController<UITableViewDataSource, UITableViewDelegate>
#property (strong, nonatomic) IBOutlet UITableView *tweetTableView;
#property (nonatomic, copy) NSArray *dataSource;
-(IBAction)refresh:(id)sender;
#end
.m
#implementation ViewController
- (void)getTimeLine {
ACAccountStore *account = [[ACAccountStore alloc] init];
ACAccountType *accountType = [account
accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
[account requestAccessToAccountsWithType:accountType
options:nil completion:^(BOOL granted, NSError *error)
{
if (granted == YES)
{
NSArray *arrayOfAccounts = [account
accountsWithAccountType:accountType];
if ([arrayOfAccounts count] > 0)
{
ACAccount *twitterAccount = [arrayOfAccounts lastObject];
/* NSString * kTwitterHashtag = #"#nasa";
NSString * kTwitterUsername = #"";
// Looking for #kTwitterHashtag or #kTwitterUsername
NSString *urlString = [[[#"http://search.twitter.com/search.json?q=%23" stringByAppendingString:(NSString *)kTwitterHashtag]
stringByAppendingString:#"+OR+%40"] stringByAppendingString:(NSString *)kTwitterUsername];
NSURL *requestURL = [NSURL URLWithString:urlString];
*/
NSURL *requestURL = [NSURL URLWithString:#"http://api.twitter.com/1/statuses/home_timeline.json"];
NSMutableDictionary *parameters =
[[NSMutableDictionary alloc] init];
[parameters setObject:#"20" forKey:#"count"];
[parameters setObject:#"1" forKey:#"include_entities"];
SLRequest *postRequest = [SLRequest
requestForServiceType:SLServiceTypeTwitter
requestMethod:SLRequestMethodGET
URL:requestURL parameters:parameters];
postRequest.account = twitterAccount;
[postRequest performRequestWithHandler:
^(NSData *responseData, NSHTTPURLResponse
*urlResponse, NSError *error)
{
self.dataSource = [NSJSONSerialization
JSONObjectWithData:responseData
options:NSJSONReadingMutableLeaves
error:&error];
if (self.dataSource.count != 0) {
dispatch_async(dispatch_get_main_queue(), ^{
[self.tweetTableView reloadData];
NSLog(#"_dataSource.count %d",_dataSource.count);
for(NSDictionary * tweet in _dataSource){
NSLog(#"tweet : %#",tweet[#"text"]);
}
});
}
}];
}
} else {
// Handle failure to get account access
}
}];
}
- (void)viewDidLoad
{
[super viewDidLoad];
_tweetTableView = [[UITableView alloc] init];
_dataSource = [[NSArray alloc] init];
[self getTimeLine];
}
-(IBAction)refresh:(id)sender{
[self getTimeLine];
[self.tweetTableView reloadData];
}
#pragma mark -
#pragma mark UITableViewDataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return _dataSource.count;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [self.tweetTableView
dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc]
initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
NSDictionary *tweet = _dataSource[[indexPath row]];
NSLog(#"tweet : %#",tweet);
cell.textLabel.text = tweet[#"text"];
return cell;
}
#end

Answer 1

self.dataSource = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableLeaves error:&error];
This is returning a string... but you are assigning it to an NSArray!