Using #objc delegate methods with multiple arguments - ios

Question

I want to be able to pass multiple arguments to a #selector() method other than only the sender itself.
Say, I have a UITextField which has a UITapGestureRecognizer, and I want some other class to be the delegate of this UITapGestureRecognizer. I write a delegate protocol for it called SomeDelegateProcotol. However, I also want to pass the instance of the UITextField to the delegate upon tap. I figured things might look something like this:
// The delegate
class Delegate: SomeDelegateProcotol {
private let textField = TextField()
func handleTapFromView(_ sender: UITapGestureRecognizer, textField: UITextField) {
print("Hey! I should handle the tap from the user.")
}
init() {
textField.delegate = self
}
}
// The protocol
#objc protocol SomeDelegateProtocol {
#objc func handletapFromView(_ sender: UITapGestureRecognizer, textField: UITextField)
}
class TextField: UITextField {
weak var delegate: SomeDelegateProtocol?
override init(frame: CGSize) {
super.init(frame: frame)
...
let gestureRecognizer = UITapGestureRecognizer(target: delegate!,
action: #selector(delegate!.handleTapFromView(_:, textField:
self)))
}
}
However, this is not the right syntax, as handleTapFromView(_:, textField: self) is invalid. This raises the following questions to which I haven't found a solution yet:
What exactly means this syntax? (_:). I assume it's passing itself, but the UITapGestureRecognizer is not created yet?
How do I successfully pass the TextField instance to the delegate alongside the sender?

Answer 1

I would suggest keeping things as simple as this,
protocol SomeDelegateProtocol: class {
func handletapFromView(_ sender: UITapGestureRecognizer, textField: UITextField)
}
class TextField: UITextField {
weak var someDelegate: SomeDelegateProtocol?
override init(frame: CGRect) {
super.init(frame: frame)
let tap = UITapGestureRecognizer.init(target: self, action: #selector(tap(_:)))
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
#objc private func tap(_ sender: UITapGestureRecognizer) {
self.someDelegate?.handletapFromView(sender, textField: self)
}
}