键盘的通知 使文本框跟随键盘移动

#define SCREEN_HEIGHT CGRectGetHeight([UIScreen mainScreen].bounds)
#define SCREEN_WIDTH CGRectGetWidth([UIScreen mainScreen].bounds)

@interface ViewController ()<UITextFieldDelegate>
{
UITextField *myTextFileld;
}

myTextFileld = [[UITextField alloc]initWithFrame:CGRectMake(0, SCREEN_HEIGHT-40, SCREEN_WIDTH,40 )];
myTextFileld.placeholder = @"请输入内容";
myTextFileld.delegate = self;
myTextFileld.borderStyle = UITextBorderStyleRoundedRect;
[self.view addSubview:myTextFileld];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(KeyBordAction:) name:UIKeyboardWillShowNotification object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(KeyBordAction:) name:UIKeyboardWillHideNotification object:nil];

- (void)KeyBordAction:(NSNotification *)not{
NSDictionary *info = not.userInfo;
CGRect frame = [info[UIKeyboardFrameEndUserInfoKey] CGRectValue];
CGFloat y = CGRectGetMinY(frame);
myTextFileld.frame = CGRectMake(0, y-40, SCREEN_WIDTH, 40);
}

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