UIView+Shake.swift

//
//  UIView+Shake.swift
//  SingleLineShakeAnimation
//
//  Created by Håkon Bogen on 24/04/15.
//  Copyright (c) 2015 haaakon. All rights reserved.
//

import UIKit

public enum ShakeDirection: Int {
    case Horizontal
    case Vertical

    private func startPosition() -> ShakePosition {
        switch self {
        case .Horizontal:
            return ShakePosition.Left
        default:
            return ShakePosition.Top
        }
    }
}

public enum Vibration {
    case Light
    case Medium
    case Heavy
    
    @available(iOS 10.0, *)
    func hapticFeedback() -> UIImpactFeedbackGenerator {
        switch self {
        case .Heavy:
            return UIImpactFeedbackGenerator(style: .heavy)
        case .Medium:
            return UIImpactFeedbackGenerator(style: .medium)
        case .Light:
            return UIImpactFeedbackGenerator(style: .light)
        }
    }
}

private struct DefaultValues {
    static let numberOfTimes = 5
    static let totalDuration: Float = 0.5
}

extension UIView {

    /**
    Shake a view back and forth for the number of times given in the duration specified.
    If the total duration given is 1 second, and the number of shakes is 5, it will use 0.20 seconds per shake.
    After it's done shaking, the completion handler is called, if specified.

    - parameter direction:     The direction to shake (horizontal or vertical motion)
    - parameter numberOfTimes: The total number of times to shake back and forth, default value is 5
    - parameter totalDuration: Total duration to do the shakes, default is 0.5 seconds
    - parameter completion:    Optional completion closure
    */
    public func shake(direction: ShakeDirection, numberOfTimes: Int = DefaultValues.numberOfTimes, totalDuration: Float = DefaultValues.totalDuration, completion: (() -> Void)? = nil) -> UIView? {
        if UIAccessibilityIsVoiceOverRunning() {
            return self
        } else {
            let timePerShake = Double(totalDuration) / Double(numberOfTimes)
            shake(forTimes: numberOfTimes, position: direction.startPosition(), durationPerShake: timePerShake, completion: completion)
            return nil
        }
    }

    public func postAccessabilityNotification(text text: String ) {
        var hasRead = false
        NSNotificationCenter.defaultCenter().addObserverForName(UIAccessibilityAnnouncementDidFinishNotification, object: nil, queue: nil) { (notification) -> Void in
            if hasRead == false {
                UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification, text)
                hasRead = true
                NSNotificationCenter.defaultCenter().removeObserver(self, name: UIAccessibilityAnnouncementDidFinishNotification, object:nil)
            }
        }
        // seems to be a bug with UIAccessability that does not allow to post a notification with text in the action when tapping a button
        let time = dispatch_time(DISPATCH_TIME_NOW, Int64(0.01 * Double(NSEC_PER_SEC)))
        dispatch_after(time, dispatch_get_main_queue()) {
            UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification, " ")
        }
    }
    
    @available(iOS 10.0, *)
    public func withHapticVibration(_ intesity: Vibration) {
        intesity.hapticFeedback().impactOccurred()
    }

    func didFinishReadingAccessabilityLabel() {
        dispatch_async(dispatch_get_main_queue(), {
            UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification, "hello world")
        })
    }

    private func shake(forTimes forTimes: Int, position: ShakePosition, durationPerShake: NSTimeInterval, completion: (() -> Void)?) {
        UIView.animateWithDuration(durationPerShake, animations: { () -> Void in

            switch position.direction {
            case .Horizontal:
                self.layer.setAffineTransform( CGAffineTransformMakeTranslation(2 * position.value, 0))
                break
            case .Vertical:
                self.layer.setAffineTransform( CGAffineTransformMakeTranslation(0, 2 * position.value))
                break
            }
            }) { (complete) -> Void in
                if (forTimes == 0) {
                    UIView.animateWithDuration(durationPerShake, animations: { () -> Void in
                        self.layer.setAffineTransform(CGAffineTransformIdentity)
                        }, completion: { (complete) -> Void in
                            completion?()
                    })
                } else {
                    self.shake(forTimes: forTimes - 1, position: position.oppositePosition(), durationPerShake: durationPerShake, completion:completion)
                }
        }
    }

}

private struct ShakePosition  {

    let value: CGFloat
    let direction: ShakeDirection

    init(value: CGFloat, direction: ShakeDirection) {
        self.value = value
        self.direction = direction
    }

    func oppositePosition() -> ShakePosition {
        return ShakePosition(value: (self.value * -1), direction: direction)
    }

    static var Left: ShakePosition {
        return ShakePosition(value: 1, direction: .Horizontal)
    }

    static var Right: ShakePosition {
        return ShakePosition(value: -1, direction: .Horizontal)
    }

    static var Top: ShakePosition {
        return ShakePosition(value: 1, direction: .Vertical)
    }

    static var Bottom: ShakePosition {
        return ShakePosition(value: -1, direction: .Vertical)
    }
    
}