How to hide the keyboard when I press return key in a UITextField?

Question

First make your file delegate for UITextField

@interface MYLoginViewController () <UITextFieldDelegate>

@end

Then add this method to your code.

- (BOOL)textFieldShouldReturn:(UITextField *)textField {        
    [textField resignFirstResponder];
    return YES;
}

Also add self.textField.delegate = self;

In viewDidLoad declare:

[yourTextField setDelegate:self];

Then, include the override of the delegate method:

-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];
    return YES;
}

Try this in Swift,

Step 1: Set delegate as self to your textField

textField.delegate = self

Step 2: Add this UITextFieldDelegate below your class declaration,

extension YourClassName: UITextFieldDelegate {
    func textFieldShouldReturn(textField: UITextField) -> Bool {
         textField.resignFirstResponder()
        return true
    }
}

In swift do like this:
First in your ViewController implement this UITextFieldDelegate For eg.

class MyViewController: UIViewController, UITextFieldDelegate {
....
}

Now add a delegate to a TextField in which you want to dismiss the keyboard when return is tapped either in viewDidLoad method like below or where you are initializing it. For eg.

override func viewDidLoad() {

    super.viewDidLoad()   
    myTextField.delegate = self
}

Now add this method.

func textFieldShouldReturn(textField: UITextField) -> Bool {

    textField.resignFirstResponder()
    return true
}

Swift 4

Set delegate of UITextField in view controller, field.delegate = self, and then:

extension ViewController: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        // don't force `endEditing` if you want to be asked for resigning
        // also return real flow value, not strict, like: true / false
        return textField.endEditing(false)
    }
}

set delegate of UITextField, and over ride, textFieldShouldReturn method, in that method just write following two lines:

[textField resignFirstResponder];
return YES;

that's it. Before writing a code dont forget to set delegate of a UITextField and set Return key type to "Done" from properties window.(command + shift + I).