I have classes defined roughly like so:

```
@interface ClassA : NSObject
@property BOOL propA;
@end

@interface ClassB : ClassA
@property BOOL propB;
@end

@interface ClassC : ClassB
@property BOOL propC;
@end

@interface ClassD : ClassC
@property BOOL propD;
@end

```

Now in my implementation file, I try the following:

```
@implementation ClassD

- (id) init
{
    self = [super init];

    if (self)
    {
        _propD = NO;
        // Fails because _propC is private, so I can't see it:
        _propC = NO;
        // Works:
        super.propC = NO;
        // Fails, because property "super.super" not found
        super.super.propB = NO;
        super.super.super.propA = NO;
    }

    return self;
}

@end

```

How can I set `propB` and `propA` in this case?