UIView.animate() : do I need a weak reference to self in the animation block? [duplicate]

Question

After some research I found out my app was using way too much energy because of several UIView animations throughout the app, where I was capturing the related UIViewController in the completion block, without making a weak reference to it.

So actually, I changed this:

func animate() {
    UIView.animate(withDuration: 0.3, animations: {
        self.label.alpha = 0.5
    }) { _ in 
        self.animate()
    }
}

Into this :

func animate() {
    UIView.animate(withDuration: 0.3, animations: {
        self.label.alpha = 0.5
    }) { [weak self] _ in 
        self?.animate()
    }
}

However, I would like to know if I need to do the same with the animation block (the self.label.alpha = 0.5 one) ?

Thank you for your help

Answer 1

No, it is not needed in this case. animations and completion are not retained by self so there is no risk of strong retain cycle.

duplicated of Is it necessary to use [unowned self] in closures of UIView.animateWithDuration(...)?

Answer 2

You don't need to use [weak self] in static function UIView.animate() You need to use weak when retain cycle is possible and animations block is not retained by self.

There is an article on medium about where [weak self] may and may not be needed

For more information:

• Automatic Reference Counting

• Closures

There might be another issue for the energy problem.