CODEWITHSUNDEEP
swiftfunctionclass
Dylan
Dylan

Reputation: 1348

Call different function in a reusable class in Swift

I created a custom text field and call a function every time the user type on it, the problem is how can I know what function was going to call.

Here is my code for custom UITextField that call a function every type.

class CustomTextField: UITextField, UITextFieldDelegate {
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        NSObject.cancelPreviousPerformRequests(
            withTarget: self,
            selector: #selector(callFunction),
            object: textField)
        self.perform(
            #selector(callFunction),
            with: textField,
            afterDelay: 0.5)
        return true
    }
    @objc func callFunction(textField: UITextField) {
         functionToBeCall()
    }
}

As you can see in my code, I need that functionToBeCall() to be change in every class I use it, and that class was reusable so I can't set a static method in it. How can I achieve that?

Upvotes: 0

Views: 56

Answers (1)

vacawama
vacawama

Reputation: 154603

Use delegation:

protocol CustomTextFieldDelegate: class {
    func customTextFieldDidChange(_ customTextField: CustomTextField)
}

class CustomTextField: UITextField, UITextFieldDelegate {
    weak var customDelegate: CustomTextFieldDelegate?

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        NSObject.cancelPreviousPerformRequests(
            withTarget: self,
            selector: #selector(callFunction),
            object: textField)
        self.perform(
            #selector(callFunction),
            with: textField,
            afterDelay: 0.5)
        return true
    }

    @objc func callFunction(textField: UITextField) {
        customDelegate?.customTextFieldDidChange(self)
    }
}

Any class that uses a CustomTextField should adopt the CustomTextFieldDelegate protocol, implement the callback function, and set itself as the customDelegate on the CustomTextField.

Example Usage:

class ViewController: UIViewController, CustomTextFieldDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()

        let customTextField = CustomTextField(frame: CGRect(x: 100, y: 100, width: 200, height: 50))
        view.addSubview(customTextField)
        customTextField.customDelegate = self
    }
    
    func customTextFieldDidChange(_ customTextField: CustomTextField) {
        print("custom field was changed")
    }
    
}

Upvotes: 3

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