Swift reusable UITextFieldDelegate

问题:

I am trying to implement a reusable UITextFieldDelegate class as follows:

class CustomTextFieldDelegate : NSObject, UITextFieldDelegate

All delegate protocol methods are implemented correctly.

In the controller, I assign the delegate to the UITextField

textField.delegate = CustomTextFieldDelegate()

The problem is that none of the delegate functions get called. However, when I implement the delegate protocol from the controller, then things work fine

class CustomTableViewController: UITableViewController, UITextFieldDelegate

Any ideas what is going on?

回答1:

If your want to reuse CustomTextFieldDelegate through out the project, you should use a Singleton instance;

textField.delegate = CustomTextFieldDelegate.sharedInstance

and the class changes

class CustomTextFieldDelegate : NSObject, UITextFieldDelegate {

    static let sharedInstance:CustomTextFieldDelegate = CustomTextFieldDelegate();

    func textFieldDidBeginEditing(textField: UITextField) {
        NSLog("textFieldDidBeginEditing ...");
    }
   //... other methods
} //F.E.