按下回车键时如何以编程方式关闭键盘iOS

我以编程方式创建了UITextField，使UITextField成为viewController的属性.我需要取消键盘和屏幕上的回车和touch .我可以让屏幕touch 屏关闭，但按Return键不起作用.

我已经了解了如何使用故事板以及通过直接分配和初始化UITextField对象而不将其创建为属性来做到这一点.可以做吗？

H

#import <UIKit/UIKitH>

@interface ViewController : UIViewController <UITextFieldDelegate>

@property (strong, atomic) UITextField *username;

@end

.m

#import "ViewControllerH"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // Do any additional setup after loading the view, typically from a nib.
    
    self.view.backgroundColor = [UIColor blueColor];
    self.username = [[UITextField alloc] initWithFrame:CGRectMake(100, 25, 80, 20)];
    self.username.placeholder = @"Enter your username";
    self.username.backgroundColor = [UIColor whiteColor];
    self.username.borderStyle = UITextBorderStyleRoundedRect;
    if (self.username.placeholder != nil) {
        self.username.clearsOnBeginEditing = NO;
    }
    _username.delegate = self; 
    
    [self.view addSubview:self.username];
    [_username resignFirstResponder];
    
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    NSLog(@"touchesBegan:withEvent:");
    [self.view endEditing:YES];
    [super touchesBegan:touches withEvent:event];
}

@end