Question

I’ve read that @synthesize will automatically create corresponding instance variables for @property and that ivars are @protected by default. But, what if I use a class extension (like below) to indicate that the @property methods are to be private?

// Photo.m
@interface Photo ()
@property (nonatomic, retain) NSMutableData *urlData;
@end

Will the corresponding ivar then be @private? Or should I explicitly declare it as @private like so?

// Photo.h
@interface Photo : Resource {
@private
    NSMutableData *urlData;
}

Answer 1

@private instance variables are a compile-time-only feature. Given that the backing ivars for @property‘s are already hidden, @private doesn’t do anything. So in essence, it’s already @private.