Capturing an ivar in a block also captures self

gistfile1.m

// Code as written:

@interface MyClass : NSObject {
  NSObject *_ivar;
}
@end

@implementation MyClass
- (void)logStuff {

  dispatch_async(dispatch_get_main_queue(), ^{
    NSLog(@"ivar: %@", _ivar);
  });

}
@end

// What I thought happened

@interface MyClass : NSObject {
  NSObject *_ivar;
}
@end

@implementation MyClass
- (void)logStuff {

  __strong id ivar = _ivar;
  dispatch_async(dispatch_get_main_queue(), ^{
    NSLog(@"ivar: %@", ivar);
  });

}
@end

// What actually happens:

@interface MyClass : NSObject {
  NSObject *_ivar;
}
@end

@implementation MyClass
- (void)logStuff {

  __strong id capturedSelf = self;
  dispatch_async(dispatch_get_main_queue(), ^{
    NSLog(@"ivar: %@", capturedSelf->_ivar);
  });

}
@end