Empty array error when parsing JSON to UILabel - ios

Question

I'm trying to parse some text from a JSON-file on my server. There's three different values I'm parsing from the file: "value1":"some_value", "value2":"some_value", "value3":"some_value".
I'm declaring a NSMutableArray called statsHome which I initializing in the viewDidLoad method, like this: statsHome = [[NSMutableArray alloc] init];
The problem is that after I have initialized the array, I need to set up a NSDictionary. And if i would do this in the table view, I would write:
NSDictionary *stats = [self.statshome objectAtIndex:indexPath.row];
But I'm not parsing these values to the table view. I want to parse them to UILabels. So what I tried was to declare new NSUInteger. Because I can't use indexPath.row in the viewDidLoad method. I called it statsIndex.
But when I launch the app it crashes and gives me this error message: Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'
The rest of the code looks like this:
#interface DEMOHomeViewController () {
NSUInteger statsIndex;
}
#end
#implementation DEMOHomeViewController
#synthesize statsHome;
#synthesize twitterFollowers;
#synthesize facebookLikes;
#synthesize instagramFollowers;
- (void)viewDidLoad
{
[super viewDidLoad];
statsHome = [[NSMutableArray alloc] init];
NSDictionary *stats = [self.statsHome objectAtIndex:statsIndex];
value1.text = [stats objectForKey:#"value1"];
value2.text = [stats objectForKey:#"value2"];
value3.text = [stats objectForKey:#"value3"];
NSURL *url1 = [[NSURL alloc] initWithString:#"the-json-file-with-the-values.php/file.json"];
NSURLRequest *request1 = [[NSURLRequest alloc] initWithURL:url1];
AFJSONRequestOperation *operation1 = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
self.statsHome = [[NSArray alloc] initWithArray:JSON];
[self.activityIndicatorView stopAnimating];
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
NSLog(#"Request Failed with Error: %#, %#", error, error.userInfo);
}];
[operation1 start];
}
#end

Answer 1

Error is correct: you are trying to get data from an array before data is set. You should do something like in code below.
- (void)viewDidLoad
{
[super viewDidLoad];
NSURL *url1 = [[NSURL alloc] initWithString:#"the-json-file-with-the-values.php/file.json"];
NSURLRequest *request1 = [[NSURLRequest alloc] initWithURL:url1];
AFJSONRequestOperation *operation1 = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
[self.activityIndicatorView stopAnimating];
[self updateDataWithJSON:JSON]; // <- Here we will update our data
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
NSLog(#"Request Failed with Error: %#, %#", error, error.userInfo);
}];
[operation1 start];
}
- (void)updateDataWithJSON:(id)JSON
{
self.statsHome = [[NSArray alloc] initWithArray:JSON];
NSDictionary *stats = [self.statsHome objectAtIndex:statsIndex];
value1.text = [stats objectForKey:#"value1"];
value2.text = [stats objectForKey:#"value2"];
value3.text = [stats objectForKey:#"value3"];
}
Let me give you an advice. Seems like your statsIndex initialised in other part of your app. In this case it's better to check if statsIndex is suitable for array length every time you access this array. Otherwise it could be a reason of app crash in some cases: For example you got your array in other controller and it has 10 elements. You select last element but reload a request in your viewDidLoad of DEMOHomeViewController. And in this time array has only 9 elements (last element was deleted already by someone else). -> Crash

Answer 2

NSURL *url = [NSURL URLWithString: [NSString stringWithFormat:#"url"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:#"GET"];
[request setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
NSString *authStr = [NSString stringWithFormat:#"%#:%#", #"usernmae", #"password"];
NSData *authData = [authStr dataUsingEncoding:NSUTF8StringEncoding];
NSString *authValue = [NSString stringWithFormat:#"Basic %#", [authData base64EncodedStringWithOptions:0]];
NSLog(#"%#",authValue);//
[request setValue:authValue forHTTPHeaderField:#"Authorization"];
[request setURL:url];
NSLog(#"%#",url);
NSError *error;
NSHTTPURLResponse *response;
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSLog(#"Response code: %ld", (long)[response statusCode]);
NSLog(#"Data is %#",data);