Actions when a user has started/ended interacting with a UITextField in iOS
In the first example one can see how you would intercept the user interacting with a textfield while writing. Similarly, there are methods in the UITextFieldDelegate that are called when a user has started and ended his interaction with a TextField.
To be able to access these methods, you need to conform to the UITextFieldDelegate protocol, and for each textfield you want to be notified about, assign the parent class as the delegate:
class SomeClass: UITextFieldDelegate…