Swift 4.2
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
if let char = string.cString(using: String.Encoding.utf8) {
let isBackSpace = strcmp(char, "\\b")
if (isBackSpace == -92) {
print("Backspace was pressed")
}
}
return true
}
Older Swift version
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
let char = string.cStringUsingEncoding(NSUTF8StringEncoding)!
let isBackSpace = strcmp(char, "\\b")
if (isBackSpace == -92) {
println("Backspace was pressed")
}
return true
}
This delegate method is not fired. The delegate is setup in
viewDidLoad()method.-1: this code works, but by accident. The documentation specifies that
stringwill be an empty string if the user deletes one or more characters.@gbk Check this link stackoverflow.com/questions/1977934/… to detect backspace even if the TextField is empty.
This answer is dangerously wrong and should be avoided. The specific return value of strcmp (other than its sign) is meaningless. The string is empty, not
\b.