How can I make an UILabel appear and disappear 5 times? - ios

Question

When I press a button, a view with a label appears. Then I want the label to disappear and reappear 5 times (with animation), each time the label reappears with different text.
I can't seem to get the any code to work to animate a UILabel and change the text. I have tried this. However, when I press the button, the loop and animations occur instantly.
The duration is a follows: 0.3, 0.6, 0.9, 1.2, 1.5
for i in 1...5 {
infoViewMsgLbl.text = randomReward(real: i) // This retrives a String
UIView.animate(withDuration: ((1.5/5)*Double(i)), delay: 0.0, options: .allowAnimatedContent, animations: {
self.infoViewMsgLbl.alpha = 0
}, completion: { finished in
UIView.animate(withDuration: ((1.5/5)*Double(i)), animations: {
self.infoViewMsgLbl.alpha = 1
})
})
print("in the loop: ", i)
}

Answer 1

You are changing duration, but leaving delay as 0 (i.e. start immediately). In these cases, you might do it the other way around, changing delay and leaving duration unchanged.
But given that you want to change the label text, I might use a timer instead:
var index = 1
Timer.scheduledTimer(withTimeInterval: 0.3, repeats: true) { [weak self] timer in
self?.infoViewMsgLbl.alpha = 0
self?.infoViewMsgLbl.text = self?.randomReward(real: index)
index += 1
if index > 5 { timer.invalidate() }
UIView.animate(withDuration: 0.3) {
self?.infoViewMsgLbl.alpha = 1
}
}

Answer 2

Maybe something like this:
func animate(alpha: CGFloat, start: Int, end: Int) {
infoViewMsgLbl.text = randomReward(real: Int(start/2)) // This retrives a String
UIView.animate(withDuration: 0.3, animations: {
self.infoViewMsgLbl.alpha = alpha
}, completion: { success in
if start + 1 <= end {
self.animate(alpha: alpha == 1.0 ? 0.0 : 1.0, start: start + 1, end: end)
}
})
}
Usage:
animate(alpha:0.0, start: 0, end: 10) //would flash a total of 5 times
Note that the duration stays 0.3 because it doesn't call the next loop until each additional 0.3 seconds has passed.