Trouble loading data for TableView from server - mysql

Question

Im using a web-service API to load information from a DB (mySQL). When transitioning to a UITableViewController, I retrieve an array that contains categories in the VieDidLoad method. However, I am not able to display the array of categories that I got into the table view cells. When I init the category NSMutubaleArray and hardcode it on the otherhand, the tableview does display the information. I am trying to understand what I'm doing wrong in the steps of loading this array and populating it onto the tableview. Here is my code:
- (void)viewDidLoad
{
[super viewDidLoad];
//When I init the _categoryList the way below, it displays the info.
//_categoryList = [[NSMutableArray alloc] initWithObjects:#"Trending",#"Sports",#"Portraits", #"Art",#"IdUser", nil];
_toCategory = [[NSString alloc]init];
//When I try to populate it from the server it doesnt work.
_categoryList = [[NSMutableArray alloc]init];
//just call the "getCategories" command from the web API
[[API sharedInstance] commandWithParams:[NSMutableDictionary dictionaryWithObjectsAndKeys:
#"getCategories",#"command",
nil]
onCompletion:^(NSDictionary *json) {
//got stream
NSArray *tempArray = [json objectForKey:#"result"];
for (int i=0;i<tempArray.count;i++){
[_categoryList insertObject:[tempArray objectAtIndex:i] atIndex:i];
}
//I verify that I was able to retrieve the array with the correct conent.
[self printArray:_categoryList];
NSLog(#"got categories");
[self.tableView reloadData];
}];
}
Any help would be greatly appreciated. Thanks!
UPDATE #1:
The JSON return is an array with NSDictioanry's. I print out its contents just to make sure, by calling the JsonArray objectForKey[‘categories’] and get this:
SwiphtMVPClone[2410:11303] Array at Index 0 = Trending
SwiphtMVPClone[2410:11303] Array at Index 1 = Sports
SwiphtMVPClone[2410:11303] Array at Index 2 = Portraits
SwiphtMVPClone[2410:11303] Array at Index 3 = Art
Right now, my app is actually crashing – getting this error:
[__NSCFDictionary isEqualToString:]: unrecognized selector sent to instance 0x72a85d0