My app is written in Swift 2.0 and needs to run on iOS 8.1 or higher. I use Xcode 7.0.
I am using a standard UITableViewController. My UITableView has only one kind of custom prototype cells CustomCell that subclasses UITableViewCell. The CustomCell has a couple of UILabels inside, all of them have clear background colour and fixed width and height. Everything is laid out in the Interface Builder.
I receive data very often (10+ times/s) from another source. The labels in my cell have to update their content based on the received data. I also need to animate the labels backgrounds colours. To do this, I use the following:
extension UIView {
func fadeOut() {
self.layer.backgroundColor = UIColor.blackColor().CGColor
UIView.animateWithDuration(2.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseOut, animations: { () -> Void in
self.layer.backgroundColor = UIColor.clearColor().CGColor
}, completion: nil)
}
}
I update the labels using the following code:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("customCell", forIndexPath: indexPath) as! CustomCell
let oldText = customLabel.text
let newText = dataForLabels[indexPath.row].custom
if newText != oldText {
cell.customLabel.fadeOut()
}
cell.customLabel.text = dataForLabels[indexPath.row].custom
return cell
}
And my update (callback) method looks like this:
var dataForLabels:[Int:(custom: String?, anotherCustom: String?)] = [:]
func updateData(CustomData data) {
for d in data {
dataForLabels[d.index] = (custom: data.custom, anotherCustom: data.anotherCustom)
}
tableView.reloadData()
}
Now, the problem itself:
When there is no change in data for specific cell/label, the animation should go on (fading effect, 2s). When the data changes, the animation should restart.
When I call reloadData(), and there was no change of data, the animation is removed/stopped, that is, the label's background colour is suddenly clear with no fading effect.
I have tried dispatching reloadData() to the main thread, but it doesn't help. I have tried using CABasicAnimation instead of animateWithDuration(), but it doesn't solve the problem either.
I tried a similar scenario, but without using a table at all (just a couple of UIViews instead of cells) and it works. The problem is when I use reloadData().
I have tried debugging it, but I am not good when it comes to disassembly. I saw that layout_if_needed() was called and somewhere there all animations were removed.
What I suspect is that when reloadData() is called, the layout manager thinks that for some reason constraints changed and there is a need to update the layout, which breaks all animations.
Is there any solution to this problem, preferably one where I can keep using Interface Builder?
Any help will be greatly appreciated.
