UITableView Crashing - iphone

Question

I have a UITableView I add as a subview of self.view and it crashes at
- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
Here is my code:
interface (in CRFeedViewController.m)
#property (assign) BOOL dataIsLoaded;
- (NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if(dataIsLoaded == YES)
{
return [self.items count];
}
else {
return 1;
}
}
// Return a cell for the index path
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Cell label
cell.textLabel.text = #"Tweet";
if (cell == nil) {
cell = [[UITableViewCell alloc] init];
}
return cell;
}
- (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];
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.items = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableLeaves error:&error];
if (self.items.count != 0) {
dataIsLoaded = YES;
[self.tableView reloadData];
}
else {
NSLog(#"No items");
}
}];
}
} else {
NSLog(#"No access");
}
}];
}
- (void) viewWillAppear:(BOOL)animated
{
[self getTimeLine];
}
- (void)viewDidLoad
{
[super viewDidLoad];
/**
* TABLE VIEW
* Add subview of the table
*/
self.items = [NSArray arrayWithObjects:#"test", nil];
CGRect tableViewRect = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
UITableView *tableView = [[UITableView alloc] initWithFrame:tableViewRect style:UITableViewStylePlain];
tableView.dataSource = self;
[self.view addSubview:tableView];
}
EDIT
Here is my complete code, I'm sorry I don't understand all of this yet, I am still very new.
.h
//
// CRFeedViewController.h
// Twitter
//
// Created by Cody Robertson on 6/27/13.
// Copyright (c) 2013 Cody Robertson. All rights reserved.
//
#import <UIKit/UIKit.h>
#import <Accounts/Accounts.h>
#import <Social/Social.h>
#interface CRFeedViewController : UIViewController <UITableViewDataSource, UITableViewDelegate>
#property (strong, nonatomic) UITableView *tableView;
#property (strong, nonatomic) NSArray *items;
#end
.m
//
// CRFeedViewController.m
// Twitter
//
// Created by Cody Robertson on 6/27/13.
// Copyright (c) 2013 Cody Robertson. All rights reserved.
//
#import "CRFeedViewController.h"
#import "CRComposeViewController.h"
#import "CRSearchViewController.h"
#interface CRFeedViewController ()
#property (assign) BOOL dataIsLoaded;
- (void) composeTweet: (id) sender;
- (void) searchTweets: (id) sender;
- (void) getTimeLine;
#end
#implementation CRFeedViewController
#synthesize dataIsLoaded;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
/**
* NAV BAR
* Add icon and button to nav bar
*/
// Add Twitter Icon as Title
UIImageView *UINavTitleLogo = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"UINavBarLogo.png"]];
UINavTitleLogo.contentMode = UIViewContentModeScaleAspectFill;
self.navigationItem.titleView = UINavTitleLogo;
// Add Search & Compose Icon
UIImage *UISearchNavButton = [UIImage imageNamed:#"Search.png"];
UIBarButtonItem *CRSearchNavButton = [[UIBarButtonItem alloc] initWithImage:UISearchNavButton style:UIBarButtonItemStylePlain target:self action:#selector(searchTweets:)];
UIImage *UIComposeNavButton = [UIImage imageNamed:#"Compose.png"];
UIBarButtonItem *CRComposeNavButton = [[UIBarButtonItem alloc] initWithImage:UIComposeNavButton style:UIBarButtonItemStylePlain target:self action:#selector(composeTweet:)];
NSArray *UINavItems = #[CRComposeNavButton, CRSearchNavButton];
self.navigationItem.rightBarButtonItems = UINavItems;
[[UINavigationBar appearance] setTitleTextAttributes:#{
UITextAttributeTextColor: [UIColor whiteColor]
}];
/**
* TAB BAR
* Add icon and label to task bar
*/
UIImage *CRFeedTabBarIcon = [UIImage imageNamed:#"Home.png"];
UITabBarItem *CRFeedTabBarItem = [[UITabBarItem alloc] initWithTitle:#"Home" image:CRFeedTabBarIcon tag:0];
self.tabBarItem = CRFeedTabBarItem;
}
return self;
}
- (void) composeTweet:(id)sender
{
/**
* PUSH VIEW TO COMPOSE
* Load the compose view
*/
CRComposeViewController *CRCompose = [[CRComposeViewController alloc] init];
CRCompose.title = #"New Tweet";
[self.navigationController pushViewController:CRCompose animated:YES];
}
- (void) searchTweets:(id)sender
{
/**
* PUSH VIEW TO SEARCH
* Load the search view
*/
CRSearchViewController *CRSearch = [[CRSearchViewController alloc] init];
CRSearch.title = #"Search";
[self.navigationController pushViewController:CRSearch animated:YES];
}
- (NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if(dataIsLoaded == YES)
{
return [self.items count];
}
else {
return 1;
}
}
// Return a cell for the index path
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Cell label
cell.textLabel.text = #"Tweet";
if (cell == nil) {
cell = [[UITableViewCell alloc] init];
}
return cell;
}
- (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];
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.items = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableLeaves error:&error];
if (self.items.count != 0) {
dataIsLoaded = YES;
[self.tableView performSelectorOnMainThread:#selector(reloadData) withObject:nil waitUntilDone:YES];
}
else {
NSLog(#"No items");
}
}];
}
} else {
NSLog(#"No access");
}
}];
}
- (void) viewWillAppear:(BOOL)animated
{
[self getTimeLine];
}
- (void)viewDidLoad
{
[super viewDidLoad];
/**
* TABLE VIEW
* Add subview of the table
*/
self.items = [NSArray arrayWithObjects:#"test", nil];
CGRect tableViewRect = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
UITableView *tableView = [[UITableView alloc] initWithFrame:tableViewRect style:UITableViewStylePlain];
tableView.delegate = self;
tableView.dataSource = self;
[self.view addSubview:tableView];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

You should call the reloadData method on the main thread:
[self.tableView performSelectorOnMainThread:#selector(reloadData) withObject:nil waitUntilDone:YES];
Not sure if this is causing your crash, but you need to init your cells with the reuse identifier:
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier;
I would recommend that you post the trace logged in Xcode when the app crashes. It will give a better understanding as to why your app is crashing.

Answer 2

Add the delegate first so those methods are ran. Don't forget to subscribe to the delegate in your .h as well.
ViewController.h
#interface ViewController : UIViewController <UITableViewDelegate,UITableViewDataSource>
#property (nonatomic, strong) NSArray *items;
// In your viewDidLoad
tableView.dataSource = self;
tableView.delegate = self;

Answer 3

You return 1 cell even if you don't have data. You should return 0

Answer 4

If the error is happening in the numberOfRows method, then the culprit is most likely:
[self.items count];
The most likely case this causes an error is if self.items does not have a count method. In your viewDidLoad, you set it to an NSArray, which does have a count method. However, there is one other place you set self.items:
self.items = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableLeaves error:&error];
The result of that method most likely does not have a count method, and therefore is not an NSArray, yet you are storing it in a variable that is defined as NSArray.
After that line, above, put the following code:
NSLog(#"Class: %#", NSStringFromClass([self.items class]));
If the output is not NSArray, you most likely have a programming error.
Also, it looks like you are using multiple threads, to read/write to the same variable. This is usually not a good idea without implementing some sort of thread safety on those properties.