Question about HTTP exception handling on iPhone - iphone

Question

I try to add a method to handle exception, but the program just crashes instead of pop up an AlertView.
1) I set up the connection:
-(void)connect:(NSString *)strURL
{
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:strURL]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (theConnection)
{
// receivedData is declared as a method instance elsewhere
receivedData = [[NSMutableData data] retain];
}
else
{
// inform the user that the download could not be made
}
}
2)I add method to receive data and conver it to string:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// append the new data to the receivedData
// receivedData is declared as a method instance elsewhere
[receivedData appendData:data];
ReturnStr = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
}
3)I add exception handle method:
-(void) connection:(NSURLConnection *)connection didFailWithError: (NSError *)error {
UIAlertView *errorAlert = [[UIAlertView alloc]
initWithTitle: [error localizedDescription]
message: [error localizedFailureReason]
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[errorAlert show];
}
After I change the strURL to a wrong url, the program just crashes. Any ideas why the AlertView doesn't pop up?

Answer 1

Check out the error handling that I've got in this file. If you set the URL to an invalid URL, it does (in my example) come back with a nice dialog error message. I just tried it to be sure.
Relevant code in the linked file is:
-(void) connection:(NSURLConnection *)connection
didFailWithError: (NSError *)error {
UIAlertView *errorAlert = [[UIAlertView alloc]
initWithTitle: [error localizedDescription]
message: [error localizedFailureReason]
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[errorAlert show];
[errorAlert release];
[activityIndicator stopAnimating];
NSLog (#"Connection Failed with Error");
}