XCode 3.2.1 doesn't show contents of NSMutableArray when debugging?

Question

I am struggling to understand why the following code doesn't show an array with any contents when I debug in XCode and yet the NSLog clearly displays contents, as does GDB using po?

- (IBAction)action: (id)sender {

NSMutableArray *btnTitles = [NSMutableArray arrayWithObject: @"Open in Safari"];
NSLog(@"%@",[btnTitles description]); // in xcode - btnTitles shows 0 elements, nslog shows 1?

if ([MFMailComposeViewController canSendMail]) {
 [btnTitles addObject: @"Email Article"];
}
NSLog(@"%@, %i",[btnTitles description], [btnTitles count]); // in xcode still shows 0 items, nslog shows 2

I am using Snow Leopard and Xcode 3.2.1 - and at first I thought my variable was being released, however the NSLog and using GDB seem to indicate that everything is fine. However when I hover over the btnTitles variable it shows - (variable 0 objects). Similarly, if I do Open In Window for that variable, it has a title: btnTitles[(null)()-(null)] and it shows variable, 0 objects). Yet in the console I am seeing:

2009-12-20 14:29:03.352 MyApp[11125:207] (
    "Open in Safari"
)
2009-12-20 14:29:05.499 MyApp[11125:207] (
    "Open in Safari",
    "Email Article"
), 2

This has me stumped - the code looks like it should be ok - I am initialising the variable correctly (I have tried doing retain as well).

Can anyone spot what I am doing wrong, or is this a bug in the the new XCode on Snow Leopard?

Tim

Answer 1

when you try to show the array's contents in GDB, are you sure that you've already executed the lines that add the strings to it?

Answer 2

NSArrays are objects. They aren't supposed to show up as regular C arrays whose contents you can browse simply by looking at its starting memory address.