animateWithDuration lacks completion block, WatchOS 2 - watchkit

Question

watchOS 2 does not have any kind of completion block in its animateWithDuration function. I'm working on a game that requires running code after an animation is completed. Are there any work arounds? Perhaps using key-value observation? The alternative would be to use a timer that matches up with the length of the animation but that's non-ideal for obvious reasons.

Answer 1

NSOperation didn't work for me too. I am just using the following solution for now until Apple officially adds a completion block. Not ideal but it works. I have opened a Radar. Maybe Apple would add a completion block in a future seed of watchOS 2.
This extension adds an animateWithDuration method that takes a completion block. And the completion block is called after the duration of the animation block.
extension WKInterfaceController {
func animateWithDuration(duration: NSTimeInterval, animations: () -> Void, completion: (() -> Void)?) {
animateWithDuration(duration, animations: animations)
let completionDelay = dispatch_time(DISPATCH_TIME_NOW, Int64(duration * Double(NSEC_PER_SEC)))
dispatch_after(completionDelay, dispatch_get_main_queue()) {
completion?()
}
}
}

Answer 2

Try to extend animateWithDuration method with a completion block in your WKInterfaceController
Obj-C version (Thanks #PunnetSethi):
- (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^)(void))completion{
[self animateWithDuration:duration animations:animations];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(duration * NSEC_PER_SEC)), dispatch_get_main_queue(), completion);
}
Working on real Watch with WatchOS2

Answer 3

Swift 4
advanced animate() method for watchOS:
Repeatable
Reversible
Stoppable
with completion block
import Foundation
import WatchKit
protocol Animatable: class {
func animate(forKey key: String,duration: TimeInterval, repeatCount count: CGFloat, autoreverses: Bool, animations: #escaping () -> Void, reverseAnimations: (() -> Void)?, completion: (() -> Void)?)
func stopAnimations()
}
extension Animatable {
func animate(forKey key: String, duration: TimeInterval, repeatCount count: CGFloat, autoreverses: Bool, animations: #escaping () -> Void, reverseAnimations: (() -> Void)?, completion: (() -> Void)?) {}
func stopAnimations() {}
}
extension WKInterfaceController: Animatable {
private struct AssociatedKeys {
static var animsDesc = "_animsDesc"
static var stopDesc = "_stopDesc"
}
var animations: [String: (() -> Void)?] {
get {return objc_getAssociatedObject(self, &AssociatedKeys.animsDesc) as? [String: (() -> Void)?] ?? [:]}
set {objc_setAssociatedObject(self, &AssociatedKeys.animsDesc, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)}
}
var animationStopStates: [String: Bool] {
get {return objc_getAssociatedObject(self, &AssociatedKeys.stopDesc) as? [String: Bool] ?? [:]}
set {objc_setAssociatedObject(self, &AssociatedKeys.stopDesc, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)}
}
func animate(forKey key: String, duration: TimeInterval, repeatCount count: CGFloat = 1.0, autoreverses: Bool = false, animations: #escaping () -> Void, reverseAnimations: (() -> Void)? = nil, completion: (() -> Void)? = nil) {
let isStopped = self.animationStopStates[key] ?? false
if isStopped {
completion?()
return
}
self.setAnimations(key, reverse: reverseAnimations)
let count = count - 1
let deadline = DispatchTime.now() + duration
self.animate(withDuration: duration, animations: animations)
DispatchQueue.main.asyncAfter(deadline: deadline) {
var deadline2 = DispatchTime.now()
if autoreverses, let rev = reverseAnimations {
self.animate(withDuration: duration, animations: rev)
deadline2 = DispatchTime.now() + duration
}
DispatchQueue.main.asyncAfter(deadline: deadline2, execute: {
if !count.isEqual(to: .infinity) && count <= 0 {
completion?()
} else {
self.animate(forKey: key, duration: duration, repeatCount: CGFloat(count), autoreverses: autoreverses, animations: animations, reverseAnimations: reverseAnimations, completion: completion)
}
})
}
}
/// Stops all the currently playing animations
func stopAnimations() {
for key in self.animations.keys {
guard let rev = self.animations[key] else {return}
self.animationStopStates[key] = true
self.animate(forKey: key, duration: 0, repeatCount: 0, autoreverses: false, animations: {}, reverseAnimations: rev)
}
self.animations.removeAll()
}
private func setAnimations(_ key: String, reverse: (() -> Void)?) {
if self.animations[key] == nil {
self.animations[key] = reverse
}
}
}
How to use:
self.animate(forKey: "custom_anim1", duration: 1.0, repeatCount: .infinity, autoreverses: true, animations: {[unowned self] in
self.myButton.setHeight(100)
}, reverseAnimations: { [unowned self] in
self.myButton.setHeight(120)
}) {
print("Animation stopped!")
}
To stop all the animations:
self.stopAnimations()

Answer 4

You can use this extension. It's a better solutions because it doesn't rely on time like dispatching a block of code after the same amount of time as your animation with a delay. And it's elegant.
extension WKInterfaceController {
func animate(withDuration duration: TimeInterval,
animations: #escaping () -> Swift.Void,
completion: #escaping () -> Swift.Void) {
let queue = DispatchGroup()
queue.enter()
let action = {
animations()
queue.leave()
}
self.animate(withDuration: duration, animations: action)
queue.notify(queue: .main, execute: completion)
}
}
And you can use it, easily like this:
self.animate(withDuration: 0.2, animations: {
//your animation code
}, completion: {
//to do after you animation
})