Auto property synthesis (@property) and inheritance

I’d suggest to explicitly synthesize the property on your MutableCar implementation. As in:

@implementation MutableCar

@synthesize name;

@end

That way clang won’t try to use autosynthesis

Edit:

If you don’t want to use encapsulation and for other reason you need to access the ivar from the parent class, then you need to do a little bit more effort:

First the Car .h file remains the same (I added a printVar method to print the ivar and property):

@interface Car : NSObject

- (void)printVar;

@property (strong, readonly) NSString *name;

@end

Now on the .m file, I’m implementing the printVar method and also adding a class extension to tell clang to create the setter:

// Private class extension, causes setName: to be created but not exposed.
@interface Car ()

@property (strong, readwrite) NSString *name;

@end

@implementation Car

- (void)printVar
{
    NSLog(@"<Car> Hello %@, ivar: %@", self.name, _name);
}

@end

Now you can create your MutableCar.h as before:

@interface MutableCar : Car

@property (strong, readwrite) NSString *name;

@end

and your MutableCar.m should looks like this:

@implementation MutableCar

@dynamic name;

- (void)printVar
{
    [super printVar];
    NSLog(@"<MutableCar> Hello %@", self.name);
}

@end

That way the _name ivar on the parent is actually written using the parent setter and you can access it.