Cannot open files - errors with "unrecognized selector sent to instance"

Question

I installed 10.5 on MBP and noticed that there is a problem with the file dialog box. Everytime I try to 'Open a file' from any app (Firefox, Word etc...) it does not bring up the file dialog. Instead it throws this error in the console:
10/27/07 12:36:29 PM Microsoft Word[373] * -[NSNavSegmentSwitchControl initWithFrame:pullsDown:]: unrecognized selector sent to instance 0x1b9c5dd0
10/27/07 12:36:29 PM Microsoft Word[373] Exception raised!: * -[NSNavSegmentSwitchControl initWithFrame:pullsDown:]: unrecognized selector sent to instance 0x1b9c5dd0
10/27/07 12:44:17 PM firefox-bin[398] * -[NSNavSegmentSwitchControl initWithFrame:pullsDown:]: unrecognized selector sent to instance 0x17dcf430
10/27/07 12:44:17 PM firefox-bin[398] Exception raised!: * -[NSNavSegmentSwitchControl initWithFrame:pullsDown:]: unrecognized selector sent to instance 0x17dcf430
To test this, just launch Firefox and go to File->Open File... and if you don't see the File dialog then you have the problem. I have reinstalled from CD but same problem. I installed 10.5 on an iMac G5 and do not see this problem.
Any thoughts on what can be done. Its a little difficult to use the computer if I can't open or save files
Thanks,
-- John Mac.

Answer 1

RayNewbie wrote:
I think the recommendation was to make sure the object you got from your nib was an instance of the class you expected. This sounds like an especially good idea given the difference in behavior on the two platforms. For example:
if (cell2 == nil)
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self options:nil];
cell2 = [nib objectAtIndex:0];
// debug code aka introspection
if ([cell2 isMemberOfClass:[CustomCell class]])
NSLog(@"%@ is CustomCell", cell2);
else {
NSLog (@"%@ is not CustomCell", cell2);
That is fairly limiting and isn't good practice. You see that approach more in C++, which isn't as strong an object-oriented language as Objective-C. Even in C++ though, there are better ways to handle it.
In Objective-C, it is pretty easy. Look at it from the perspective of what you want to do. Then, you ask the object if it can do what you want via "respondsToSelector:"