Unable to use Block

Question

Hi, I am getting an error in this method in a class implementation. The error is coming in the Block and i am just not sure what to do for it. The error says  "__NSConcreteGlobalBlock", referenced from:.... symbol not found"."
- (IBAction) loadComposition:(id)sender{
          void (^handler)(NSInteger);
  NSOpenPanel *panel = [NSOpenPanel openPanel];
          [panel setAllowedFileTypes:[NSArray arrayWithObjects: @"qtz", nil]];
          handler = ^(NSInteger result) {
  if (result == NSFileHandlingPanelOKButton) {
       NSLog(@"Inside If");
Can someone please advise. The compiler version of the project is System default (GCC 4.2) and I am writing this application for Mac platform.
And if I change the compiler version to LLVM GCC 4.2, I get the error message "error: can't exec '/Developer/usr/bin/llvm-gcc-4.2' (No such file or directory)".

Answer 1

Upgraded XCode to version 4 from 3.2 and it worked. Had to make sure that compiler is GCC 4.2.