Cannot use UIGlassButton in iOS4

I want to use UIGlassButton in my iPhone app, I have the following code in my view controller:

UIGlassButton *myButton = [[UIGlassButton alloc] initWithFrame:CGRectMake(2,2,316,50)];
[myButton addTarget:self action:@selector(myFunction:) forControlEvents:UIControlEventTouchDown];
[myButton setTitle:@"Neat button!" forState:UIControlStateNormal];
[myButton setTintColor:[UIColor colorWithWhite:0.20f alpha:1]];
[self.view addSubview:myButton];

I added the directive @class UIGlassButton; in the view controller's header file but I end up with the following error:

Undefined symbols for arch开发者_JAVA百科itecture i386:
  "_OBJC_CLASS_$_UIGlassButton", referenced from:
   objc-class-ref in ControlViewController.o
ld: symbol(s) not found for architecture i386
collect2: ld returned 1 exit status

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UIGlassButton is not an Apple component. It probably belongs to another custom library that you need to import.