How do you fix a retain cycle? Use a weak reference. A weak reference is a pointer that does not imply ownership. To fix our retain cycle, an asset should not own its holder. Edit Asset.h to make holder a weak reference:

#import <Foundation/Foundation.h>
@class Employee;

@interface Asset : NSObject
{
    NSString *label;
    __weak Employee *holder;
    unsigned int resaleValue;
}
@property (strong) NSString *label;
@property (weak) Employee *holder;
@property unsigned int resaleValue;
@end

Build and run the program. Note that all the objects are now being deallocated correctly.

In a parent-child relationship, the general rule for preventing this type of retain cycle is the parent owns the child, but the child should not own the parent.