解决思路：

监听键盘出现和消失的状态，当键盘出现时，当前视图上移，当输入完成收起键盘时，视图回到初始状态。

难点：视图向上平移的距离

原理都差不多，oc版参考代码：

self.phoneInput = [UITextField new];
  self.phoneInput.placeholder = @"请输入...";
  [self.view addSubview:self.phoneInput];


///键盘弹出 处理遮挡问题
- (void)viewWillAppear:(BOOL)animated
{
  [super viewWillAppear:animated];
  
  [[NSNotificationCenter defaultCenter] addObserver:self
                       selector:@selector(keyboardWillShow:)
                         name:UIKeyboardWillShowNotification
                        object:nil];
  [[NSNotificationCenter defaultCenter] addObserver:self
                       selector:@selector(keyboardWillHide:)
                         name:UIKeyboardWillHideNotification
                        object:nil];
}
- (void)keyboardWillShow:(NSNotification *)notification
{
 //获取处于焦点中的view
 NSArray *textFields = @[self.phoneInput];
 UIView *focusView = nil;
 for (UITextField *view in textFields) {
  if ([view isFirstResponder]) {
   focusView = view;
   break;
  }
 }
 if (focusView) {
   //获取键盘弹出的时间
   double duration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
   //获取键盘上端Y坐标
   CGFloat keyboardY = [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].origin.y;
   //获取输入框下端相对于window的Y坐标
   CGRect rect = [focusView convertRect:focusView.bounds toView:[[[UIApplication sharedApplication] delegate] window]];
   CGPoint tmp = rect.origin;
   CGFloat inputBoxY = tmp.y + focusView.frame.size.height;
   //计算二者差值
   CGFloat ty = keyboardY- inputBoxY;
   NSLog(@"position keyboard: %f, inputbox: %f, ty: %f", keyboardY, inputBoxY, ty);
   //差值小于0，做平移变换
   [UIView animateWithDuration:duration animations:^{
    if (ty < 0) {
     self.view.transform = CGAffineTransformMakeTranslation(0, ty);
    }
   }];
  }
}

- (void)keyboardWillHide:(NSNotification *)notification
{
 //获取键盘弹出的时间
 double duration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
 //还原
 [UIView animateWithDuration:duration animations:^{
   self.view.transform = CGAffineTransformMakeTranslation(0, 0);
 }];
}
///
///UITextFieldDelegate编辑完成，视图恢复原状
-(void)textFieldDidEndEditing:(UITextField *)textField
{
   self.view.frame =CGRectMake(0, 0, [[UIScreen mainScreen] bounds].size.width,[[UIScreen mainScreen] bounds].size.height);
}