IBAction sometimes not being called when touching buttons - Swift - ios

Question

I am trying to develop a word game where players click buttons to select letters.
There seems to be problem where my buttons sometimes do not register touches. It only seems to occur if there is a pause for a few seconds with no user interaction before a button touch. If the first touch works, quick follow up touches also work.
#IBAction func tileButton1(_ sender: UIButton) {
print("Tile 1 Selected")
tileSelected(tileSelected: 1)
}
#IBAction func clearButton(_ sender: Any) {
clearSelectedTiles()
}
#IBAction func SubmitButton(_ sender: Any) {
//print("Submit Button Pressed")
checkIfSubmittedWordIsValid()
}
checkIfSubmittedWordIsValid
func checkIfSubmittedWordIsValid() {
var alreadySelectedWords: [String] = []
switch currentPlayer {
case 1:
alreadySelectedWords = player1words
case 2:
alreadySelectedWords = player2words
case 3:
alreadySelectedWords = player3words
case 4:
alreadySelectedWords = player4words
default:
break
}
if currentWord.characters.count < 3 {
print("Too short")
playSound(fileName: "invalidWord", fileExtension: "aiff", volume: 1.0)
} else if alreadySelectedWords.contains(currentWord) {
print("Already picked this word")
playSound(fileName: "invalidWord", fileExtension: "aiff", volume: 1.0)
} else if wordList.contains(currentWord.lowercased()) {
print("Valid Word")
playSound(fileName: "goodWord", fileExtension: "wav", volume: 0.5)
addWordToPlayerList(word: currentWord)
} else {
print("Not in dictionary")
playSound(fileName: "invalidWord", fileExtension: "aiff", volume: 1.0)
}
clearSelectedTiles()
}
clearSelectedTiles
func clearSelectedTiles() {
tile1.alpha = 1
tile2.alpha = 1
tile3.alpha = 1
tile4.alpha = 1
tile5.alpha = 1
tile6.alpha = 1
tile7.alpha = 1
tile8.alpha = 1
tile9.alpha = 1
tile10.alpha = 1
tile11.alpha = 1
tile12.alpha = 1
tile13.alpha = 1
tile14.alpha = 1
tile15.alpha = 1
tile16.alpha = 1
selectedTiles.removeAll()
validTiles = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]
selectedWordLabel.text = ""
currentWord = ""
}
Nothing gets printed when the issue occurs. Following up quickly with a second touch will trigger the IBAction and print to log.
It seems to happen also with all my other buttons (another 15 'tile' buttons and a 'Clear' and 'Submit' button)
What am I doing wrong?
Link to video showing issue First few touches work but then weirdness.
tileSelected
func tileSelected(tileSelected: Int) {
if isTileValid(tile: tileSelected) {
selectedTiles.append(tileSelected)
var surroundingTiles: [Int] = []
switch tileSelected {
case 1:
tile1.alpha = 0.5
surroundingTiles = [2,5,6]
case 2:
tile2.alpha = 0.5
surroundingTiles = [1,3,5,6,7]
case 3:
tile3.alpha = 0.5
surroundingTiles = [2,4,6,7,8]
case 4:
tile4.alpha = 0.5
surroundingTiles = [3,7,8]
case 5:
tile5.alpha = 0.5
surroundingTiles = [1,2,6,9,10]
case 6:
tile6.alpha = 0.5
surroundingTiles = [1,2,3,5,7,9,10,11]
case 7:
tile7.alpha = 0.5
surroundingTiles = [2,3,4,6,8,10,11,12]
case 8:
tile8.alpha = 0.5
surroundingTiles = [3,4,7,11,12]
case 9:
tile9.alpha = 0.5
surroundingTiles = [5,6,10,13,14]
case 10:
tile10.alpha = 0.5
surroundingTiles = [5,6,7,9,11,13,14,15]
case 11:
tile11.alpha = 0.5
surroundingTiles = [6,7,8,10,12,14,15,16]
case 12:
tile12.alpha = 0.5
surroundingTiles = [7,8,11,15,16]
case 13:
tile13.alpha = 0.5
surroundingTiles = [9,10,14]
case 14:
tile14.alpha = 0.5
surroundingTiles = [9,10,11,13,15]
case 15:
tile15.alpha = 0.5
surroundingTiles = [10,11,12,14,16]
case 16:
tile16.alpha = 0.5
surroundingTiles = [11,12,15]
default:
// do nothing
break
}
updateValidTiles(surroundingTiles: surroundingTiles)
//print("Updated Valid Tiles")
//print(validTiles)
//print("Selected Tiles")
//print(selectedTiles)
currentWord = currentWord + boardTiles[tileSelected - 1].tileLetter
selectedWordLabel.text = currentWord
}
}

Answer 1

Try changing touch down to touch up inside, and try changing the state of the button each time it is clicked

Answer 2

I had some labels constrained to the Top Layout Guide.bottom even though I was hiding the status bar with override var prefersStatusBarHidden.
Changing the relevant label constraints to topMargin instead of Top Layout Guide.bottom has solved my problem with touches sometimes being missed.