Why is my iPhone application crashing? - iphone

Question

My application get crashing. It's loading data of all the cities, and when I click its displaying my detailed view controller.
When I am getting back from my controller, and selecting another city my application get crashed.
I am pasting my code.
#import "CityNameViewController.h"
#import "Cities.h"
#import "XMLParser.h"
#import "PartyTemperature_AppDelegate.h"
#import "CityEventViewController.h"
#implementation CityNameViewController
//#synthesize aCities;
#synthesize appDelegate;
#synthesize currentIndex;
#synthesize aCities;
/*
// The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
// Custom initialization
}
return self;
}
*/
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
self.title=#"Cities";
appDelegate=(PartyTemperature_AppDelegate *)[[UIApplication sharedApplication]delegate];
}
/*
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
*/
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
return [appDelegate.cityListArray count];
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
return 95.0f;
}
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
cell.textLabel.textColor = [[[UIColor alloc] initWithRed:0.2 green:0.2 blue:0.6 alpha:1] autorelease];
cell.detailTextLabel.textColor = [UIColor blackColor];
cell.detailTextLabel.font=[UIFont systemFontOfSize:10];
if (indexPath.row %2 == 1) {
cell.backgroundColor = [[[UIColor alloc] initWithRed:0.87f green:0.87f blue:0.87f alpha:1.0f] autorelease];
} else {
cell.backgroundColor = [[[UIColor alloc] initWithRed:0.97f green:0.97f blue:0.97f alpha:1.0f] autorelease];
}
}
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
cell.selectionStyle= UITableViewCellSelectionStyleBlue;
// cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
cell.backgroundColor=[UIColor blueColor];
}
// aCities=[appDelegate.cityListArray objectAtIndex:indexPath.row];
// cell.textLabel.text=aCities.city_Name;
cell.textLabel.text=[[appDelegate.cityListArray objectAtIndex:indexPath.row]city_Name];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
//http://compliantbox.com/party_temperature/citysearch.php?city=Amsterdam&latitude=52.366125&longitude=4.899171
NSString *url;
aCities=[appDelegate.cityListArray objectAtIndex:indexPath.row];
if ([appDelegate.cityListArray count]>0){
url=#"http://compliantbox.com/party_temperature/citysearch.php?city=";
url=[url stringByAppendingString:aCities.city_Name];
url=[url stringByAppendingString:#"&latitude=52.366125&longitude=4.899171"];
NSLog(#"url value is %#",url);
[self parseCityName:[[NSURL alloc]initWithString:url]];
}
}
-(void)parseCityName:(NSURL *)url{
NSXMLParser *xmlParser=[[NSXMLParser alloc]initWithContentsOfURL:url];
XMLParser *parser=[[XMLParser alloc] initXMLParser];
[xmlParser setDelegate:parser];
BOOL success;
success=[xmlParser parse];
if (success) {
NSLog(#"Sucessfully parsed");
CityEventViewController *cityEventViewController=[[CityEventViewController alloc]initWithNibName:#"CityEventViewController" bundle:nil];
cityEventViewController.index=currentIndex;
[self.navigationController pushViewController:cityEventViewController animated:YES];
[cityEventViewController release];
cityEventViewController=nil;
}
else {
NSLog(#"Try it Idoit");
UIAlertView *alert=[[UIAlertView alloc] initWithTitle:#"Alert!" message:#"Event Not In Radius" delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
[alert release];
}
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)dealloc {
[aCities release];
[super dealloc];
}
#end
And the error is
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSMutableArray objectAtIndex:]: index 1 beyond bounds for empty array'
*** Call stack at first throw:

Answer 1

The Array cityListArray seems to be empty when you return to the tableview. If you modify cityListArray from elsewhere I'd suggest to call [tableView reloadData] in viewWillAppear.

Answer 2

yeah its a good idea to reload the table data once its display again, that way you can be sure the data is correct. One more thing i would like to point out is if you have city names with characters like space or quotes its always a good idea to escape the url string, if not you might get unexpected results.