How to check if user doesn't write anything in 4 seconds? - ios

Question

I have the next function:
override func textViewDidChange(textView: UITextView) {
super.textViewDidChange(textView)
if textView.text.characters.count == 0 {
print("stopped")
} else {
print("typing")
}
}
So, I want the next:
For example, user is typing something and stopped in the middle of text. I want to check, if user wrote something and stopped in the middle of typing for 4 seconds to run the function stopped().
I did this:
override func textViewDidChange(textView: UITextView) {
super.textViewDidChange(textView)
if textView.text.characters.count == 0 {
print("stopped")
} else {
print("typing")
let timer = NSTimer.scheduledTimerWithTimeInterval(4.0, target: self, selector: "stopped", userInfo: nil, repeats: false)
}
}
func stopped() {
print("stopped typing")
}
but it runs my NSTimer every time. That's not what I want.
How can I run it just one time? For example to check if user didn't write anything in 4 seconds to run stopped(). Just one time.

Answer 1

You need to stop the previous timer with invalidate
var timer
override func textViewDidChange(textView: UITextView) {
super.textViewDidChange(textView)
if textView.text.characters.count == 0 {
print("stopped")
} else {
timer.invalidate()
print("typing")
timer = NSTimer.scheduledTimerWithTimeInterval(4.0, target: self, selector: "stopped", userInfo: nil, repeats: false)
}
}

Answer 2

You'll have to keep a reference on your timer and invalidate it whenever textViewDidChange is called, something like that :
var textViewTimer : NSTimer?
override func textViewDidChange(textView: UITextView) {
super.textViewDidChange(textView)
textViewTimer.invalidate()
if textView.text.characters.count == 0 {
print("stopped")
} else {
print("typing")
textViewTimer = NSTimer.scheduledTimerWithTimeInterval(4.0, target: self, selector: "stopped", userInfo: nil, repeats: false)
}
}
func stopped() {
print("stopped typing")
}

Answer 3

Here is a solution for Swift 5
var textViewTimer: Timer?
override func textViewDidChange(textView: UITextView) {
textViewTimer.invalidate()
print("typing")
textViewTimer = Timer.scheduledTimer(timeInterval: 4.0, target: self, selector: #selector(typingStopped), userInfo: nil, repeats: false)
}
}
#objc func typingStopped() {
print("stopped")
}