How to set screen brightness with fade animations?

Question

Is it possible to animate the screen brightness change on iOS 5.1+? I am using [UIScreen mainScreen] setBrightness:(float)] but I think that the abrupt change i

Answer 1

I ran into issues with the accepted answer when attempting to animate to another value with a previous animation in progress. This solution cancels an in-progress animation and animates to the new value:

extension UIScreen {

    func setBrightness(_ value: CGFloat, animated: Bool) {
        if animated {
            _brightnessQueue.cancelAllOperations()
            let step: CGFloat = 0.04 * ((value > brightness) ? 1 : -1)
            _brightnessQueue.add(operations: stride(from: brightness, through: value, by: step).map({ [weak self] value -> Operation in
                let blockOperation = BlockOperation()
                unowned let _unownedOperation = blockOperation
                blockOperation.addExecutionBlock({
                    if !_unownedOperation.isCancelled {
                        Thread.sleep(forTimeInterval: 1 / 60.0)
                        self?.brightness = value
                    }
                })
                return blockOperation
            }))
        } else {
            brightness = value
        }
    }

}

private let _brightnessQueue: OperationQueue = {
    let queue = OperationQueue()
    queue.maxConcurrentOperationCount = 1
    return queue
}()