如何以编程方式快速创建UITextField事件？

Question

I've checked a few post but couldn't find clean explanation about it. How can I create UITextField event programmatically ?

Answer 1

start Event

yourTextField.addTarget(self, action: "myTargetEditingDidBeginFunction:", forControlEvents: UIControlEvents.EditingDidBegin)

func myTargetEditingDidBeginFunction(textField: UITextField) {
// do your stuff
}

remove Event

 yourTextField.addTarget(self, action: "myTargetEditingDidEndFunction:", forControlEvents: UIControlEvents.EditingDidEnd)

func myTargetEditingDidEndFunction(textField: UITextField) {
// user touch field
}

some other delegate methods

protocol UITextFieldDelegate : NSObjectProtocol {

    optional func textFieldShouldBeginEditing(textField: UITextField) -> Bool // return NO to disallow editing.
    optional func textFieldDidBeginEditing(textField: UITextField) // became first responder
    optional func textFieldShouldEndEditing(textField: UITextField) -> Bool // return YES to allow editing to stop and to resign first responder status. NO to disallow the editing session to end
    optional func textFieldDidEndEditing(textField: UITextField) // may be called if forced even if shouldEndEditing returns NO (e.g. view removed from window) or endEditing:YES called

    optional func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool // return NO to not change text

    optional func textFieldShouldClear(textField: UITextField) -> Bool // called when clear button pressed. return NO to ignore (no notifications)
    optional func textFieldShouldReturn(textField: UITextField) -> Bool // called when 'return' key pressed. return NO to ignore.
}

from swift docs:

struct UIControlEvents : RawOptionSetType {
    init(_ rawValue: UInt)
    init(rawValue: UInt)

    static var TouchDown: UIControlEvents { get } // on all touch downs
    static var TouchDownRepeat: UIControlEvents { get } // on multiple touchdowns (tap count > 1)
    static var TouchDragInside: UIControlEvents { get }
    static var TouchDragOutside: UIControlEvents { get }
    static var TouchDragEnter: UIControlEvents { get }
    static var TouchDragExit: UIControlEvents { get }
    static var TouchUpInside: UIControlEvents { get }
    static var TouchUpOutside: UIControlEvents { get }
    static var TouchCancel: UIControlEvents { get }

    static var ValueChanged: UIControlEvents { get } // sliders, etc.

    static var EditingDidBegin: UIControlEvents { get } // UITextField
    static var EditingChanged: UIControlEvents { get }
    static var EditingDidEnd: UIControlEvents { get }
    static var EditingDidEndOnExit: UIControlEvents { get } // 'return key' ending editing

    static var AllTouchEvents: UIControlEvents { get } // for touch events
    static var AllEditingEvents: UIControlEvents { get } // for UITextField
    static var ApplicationReserved: UIControlEvents { get } // range available for application use
    static var SystemReserved: UIControlEvents { get } // range reserved for internal framework use
    static var AllEvents: UIControlEvents { get }
}

Answer 2

Swift 4.2 :

This example perform "editingChanged" event but you may modify it to use for any other UITextField events .

    MyTextField.addTarget(self, action: #selector(MyTextField_EditingChanged)
                              , for: UIControl.Event.editingChanged)

    @objc func MyTextField_EditingChanged(textField: UITextField) {
      print(textField.text)
    }