iOS如何实现防键盘遮挡

@interface ViewController ()<UITextFieldDelegate>
@property(nonatomic,strong)UITextField* tf;
@end
@implementation ViewController
- (void)viewDidLoad {
 [super viewDidLoad];
 self.tf = [[UITextField alloc]initWithFrame:CGRectMake(10, 600, 100, 20)];
 self.tf.delegate = self;
 self.tf.backgroundColor = [UIColor blackColor];
 [self.view addSubview:self.tf];

}
#pragma mark life Circle
-(void)viewWillAppear:(BOOL)animated{
 [super viewWillAppear:animated];

 //后台切换到前台通知
 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillEnterForeground)name:UIApplicationWillEnterForegroundNotification object:nil];
 [[NSNotificationCenter defaultCenter] addObserver:self
            selector:@selector(keyboardWillHide:)
             name:UIKeyboardWillHideNotification
            object:nil];

 [self.view endEditing:YES];
}
- (void)applicationWillEnterForeground{
 [self.view endEditing:YES];
}
-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
 [self.view endEditing:YES];
}

#pragma mark UITextFieldDelegate
-(void)textFieldDidBeginEditing:(UITextField *)textField{

 //第一个cell不往上弹输入框的位置
 // if(indexPath.row!=0){
 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillChange:) name:UIKeyboardWillChangeFrameNotification object:nil];
 // }
}

-(void)textFieldDidEndEditing:(UITextField *)textField{
}
#pragma mark 键盘操作
- (void)keyboardWillChange:(NSNotification *)note
{
 NSDictionary *userInfo = note.userInfo;
 CGFloat duration = [userInfo[@"UIKeyboardAnimationDurationUserInfoKey"] doubleValue];
 CGRect keyFrame = [userInfo[@"UIKeyboardFrameEndUserInfoKey"] CGRectValue];
 //这个64是我减去的navigationbar加上状态栏20的高度,可以看自己的实际情况决定是否减去;
 CGFloat moveY = keyFrame.origin.y -self.tf.frame.origin.y-self.tf.frame.size.height;
 NSLog(@"%f",moveY);
 [UIView animateWithDuration:duration animations:^{
  self.view.transform = CGAffineTransformMakeTranslation(0, moveY);
 }];
}

- (void)keyboardWillHide:(NSNotification *)nsnotification
{
 [[NSNotificationCenter defaultCenter]removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
 [UIView animateWithDuration:0.2 animations:^{
  self.view.transform = CGAffineTransformMakeTranslation(0, 0);
 }];
}

@end