ViewController.h:
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController <UITextFieldDelegate>
@end
ViewController.m:
#import "ViewController.h"
@interface ViewController ()
@property (nonatomic, strong) UITextField *textField;
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.textField.delegate = self;
}