Question regarding @weakify and @strongify

[ghost]

I've just started using the @weakify and @strongify macros from EXTScope.h and have a quick question about their proper usage.

If used with a method such as UIView's animateWithDuration:animations:completion: do I need to use @strongify in each block I reference the variable passed to @weakify?

For instance, is this the correct usage:

NSTimeInterval duration = 0.125;
@weakify(self);
[UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionCurveEaseIn animations:^{
    @strongify(self);
    [self.flashView setAlpha:1.0f];
} completion:^(BOOL finished) {
    [UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
        @strongify(self);
        [self.flashView setAlpha:0.0f];
    } completion:^(BOOL finished) {
        @strongify(self);
        self.flashing = NO;
    }];
}];

[jspahrsummers]

Yes, that's correct. Using it within only one of those blocks means you'd still capture self strongly in the others.

However, in this particular case, that won't actually cause a permanent retain cycle. Since animations are transitory in nature, the cycle will eventually be broken when the animation completes naturally (or is interrupted).

I generally don't recommend the weak/strong dance for ephemeral things like animations and network requests.

[ghost]

Okay, cool. Thanks @jspahrsummers

Appreciate your comment about animation blocks and the like; I'd not actually considered that 👍

[jspahrsummers]

No problem! ✌️