Parsing JSON to Table View error index (19) beyond bounds (19) - ios

Question

I'm parsing a JSON file to a table view in my iPhone app.
This is my code:
#import "DEMOSecondViewController.h"
#import "DEMONavigationController.h"
#import "PostsObject.h"
#import "RNBlurModalView.h"
#define CELL_CONTENT_WIDTH 320.0f
#define CELL_CONTENT_MARGIN 10.0f
#define FONT_SIZE 14.0f
#interface DEMOSecondViewController ()
{
NSInteger refreshIndex;
NSArray *fbPost;
NSArray *pic;
NSArray *published;
}
#end
#implementation DEMOSecondViewController
#synthesize tweets;
#synthesize changeData;
- (void)refreshChannels:(id)sender {
if (tweets.count == 0) return;
// disable UI
self.title = #"Updating...";
self.navigationController.view.userInteractionEnabled = YES;
refreshIndex = 0;
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = #"Posts";
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Menu"
style:UIBarButtonItemStylePlain
target:(DEMONavigationController *)self.navigationController
action:#selector(showMenu)];
self.myTableView.separatorColor = [UIColor clearColor];
changeData.selectedSegmentIndex = 0;
[changeData addTarget:self action:#selector(segmentedControlSelectedIndexChanged:) forControlEvents:UIControlEventValueChanged];
[self issueLoadRequest];
}
- (void)segmentedControlSelectedIndexChanged:(id)sender
{
[self issueLoadRequest];
}
#pragma mark - Table view data source
- (void)issueLoadRequest
{
if (changeData.selectedSegmentIndex == 0) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSData* data = [NSData dataWithContentsOfURL:[NSURL URLWithString:#"website.php"]];
[self performSelectorOnMainThread:#selector(receiveData:) withObject:data waitUntilDone:YES];
});
} else if (changeData.selectedSegmentIndex == 1){
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSData* data = [NSData dataWithContentsOfURL:[NSURL URLWithString:#"website.php"]];
[self performSelectorOnMainThread:#selector(receiveData:) withObject:data waitUntilDone:YES];
});
} else if (changeData.selectedSegmentIndex == 2) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSData* data = [NSData dataWithContentsOfURL:[NSURL URLWithString:#"website.php"]];
[self performSelectorOnMainThread:#selector(receiveData:) withObject:data waitUntilDone:YES];
});
}
}
- (void)receiveData:(NSData *)data {
if (changeData.selectedSegmentIndex == 0) {
self.tweets = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
[self.myTableView reloadData];
} else if (changeData.selectedSegmentIndex == 1) {
self.tweets1 = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
[self.myTableView reloadData];
} else if (changeData.selectedSegmentIndex == 2) {
self.tweets2 = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
[self.myTableView reloadData];
}
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if (changeData.selectedSegmentIndex == 0) {
return self.tweets.count;
} else if (changeData.selectedSegmentIndex == 1) {
return self.tweets1.count;
} else {
return self.tweets2.count;
}
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *simpleTableIdentifier = #"PostsObject";
// The element in the array is going to be a dictionary. I JUST KNOW THIS. The key for the tweet is "text".
NSDictionary *tweet = [self.tweets objectAtIndex:indexPath.row];
NSDictionary *tweet1 = [self.tweets1 objectAtIndex:indexPath.row];
NSDictionary *tweet2 = [self.tweets2 objectAtIndex:indexPath.row];
PostsObject *cell = (PostsObject *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
if (cell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"PostsObject" owner:self options:nil];
cell = [nib objectAtIndex:0];
}
if (changeData.selectedSegmentIndex == 0) {
cell.fbPost.text = [tweet objectForKey:#"message"];
cell.published.text = [tweet objectForKey:#"published"];
cell.pic.image = [UIImage imageNamed:#"facebook_icon.png"];
} else if (changeData.selectedSegmentIndex == 1) {
cell.fbPost.text = [tweet1 objectForKey:#"tweet"];
cell.published.text = [tweet1 objectForKey:#"posted"];
cell.pic.image = [UIImage imageNamed:#"twitter_icon.png"];
} else if (changeData.selectedSegmentIndex == 2) {
cell.fbPost.text = [tweet2 objectForKey:#"message"];
cell.published.text = [tweet objectForKey:#"published"];
cell.pic.image = [UIImage imageNamed:#"twitter_icon.png"];
}
return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 96;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if (changeData.selectedSegmentIndex == 0) {
//Öppna länken eller liknande
int storyIndex = [indexPath indexAtPosition: [indexPath length] - 1];
NSString * storyLink = [[tweets objectAtIndex: storyIndex] objectForKey:#"message"];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:storyLink]];
RNBlurModalView *modal = [[RNBlurModalView alloc] initWithViewController:self title:#"Message" message:storyLink];
[modal show];
// Spit out some pretty JSON for the tweet that was tapped. Neato.
NSString *formattedJSON = [[NSString alloc] initWithData:[NSJSONSerialization dataWithJSONObject:[self.tweets objectAtIndex:indexPath.row] options:NSJSONWritingPrettyPrinted error:nil] encoding:NSUTF8StringEncoding];
NSLog(#"tweet:\n%#", formattedJSON);
} else if (changeData.selectedSegmentIndex == 1) {
//Öppna länken eller liknande
int storyIndex = [indexPath indexAtPosition: [indexPath length] - 1];
NSString * tweetLink = [[tweets objectAtIndex: tweetLink] objectForKey:#"tweet"];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:tweetLink]];
RNBlurModalView *modal = [[RNBlurModalView alloc] initWithViewController:self title:#"Message" message:tweetLink];
[modal show];
// Spit out some pretty JSON for the tweet that was tapped. Neato.
NSString *formattedJSON = [[NSString alloc] initWithData:[NSJSONSerialization dataWithJSONObject:[self.tweets objectAtIndex:indexPath.row] options:NSJSONWritingPrettyPrinted error:nil] encoding:NSUTF8StringEncoding];
NSLog(#"tweet:\n%#", formattedJSON);
} else if (changeData.selectedSegmentIndex == 2) {
//Öppna länken eller liknande
int storyIndex = [indexPath indexAtPosition: [indexPath length] - 1];
NSString * storyLink = [[tweets objectAtIndex: storyIndex] objectForKey:#"message"];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:storyLink]];
RNBlurModalView *modal = [[RNBlurModalView alloc] initWithViewController:self title:#"Message" message:storyLink];
[modal show];
// Spit out some pretty JSON for the tweet that was tapped. Neato.
NSString *formattedJSON = [[NSString alloc] initWithData:[NSJSONSerialization dataWithJSONObject:[self.tweets objectAtIndex:indexPath.row] options:NSJSONWritingPrettyPrinted error:nil] encoding:NSUTF8StringEncoding];
NSLog(#"tweet:\n%#", formattedJSON);
}
}
#end
When I launch the app I see that it parses the data correct to the table view. But when I begin to scroll down in the list the app crashes and gives me this strange error:
Terminating app due to uncaught exception 'NSRangeException', reason: '-[__NSCFArray objectAtIndex:]: index (19) beyond bounds (19)
Can someone please help me with this?

Answer 1

You shouldn't do this:
// The element in the array is going to be a dictionary. I JUST KNOW THIS. The key for the tweet is "text".
NSDictionary *tweet = [self.tweets objectAtIndex:indexPath.row];
NSDictionary *tweet1 = [self.tweets1 objectAtIndex:indexPath.row];
NSDictionary *tweet2 = [self.tweets2 objectAtIndex:indexPath.row];
because you can't guarantee that all of the arrays have the same number of items in them. Check your configuration attribute (selectedSegmentIndex) before trying to access only the appropriate array.