ios - 在输入附件 View 中显示带有 UITextField 的键盘

Question

我有一个 buttonA，当单击 buttonA 时，我希望键盘在 inputAccessoryView 中显示一个 UITextField。有没有一种方法可以手动显示键盘并设置 inputAccessoryView 而最初没有 UITextField？

谢谢。

Answer 1

如果没有可以成为第一响应者的对象，则无法召唤键盘。有两种解决方法:

• 子类UIView 并在其中实现UIKeyInput 协议(protocol)。例如:

  在你的 .h 文件中:

  @interface InputObject : UIView<UIKeyInput>
  @property (nonatomic, copy) NSString *text;
  @property (nonatomic, strong) UIView *inputAccessoryView; // You must override inputAccessoryView , since it's readonly by default
  @end
  

  在您的 .m 文件中，实现协议(protocol):

  - (BOOL)canBecomeFirstResponder
  {
      return YES;
  }
  
  - (BOOL)hasText
  {
      return [self.text length];
  }
  
  - (void)insertText:(NSString *)text
  {
      NSString *selfText = self.text ? self.text : @"";
      self.text = [selfText stringByAppendingString:text];
      [[NSNotificationCenter defaultCenter] postNotificationName:kInputObjectTextDidChangeNotification object:self];
  }
  
  - (void)deleteBackward
  {
      if ([self.text length] > 0)
          self.text = [self.text substringToIndex:([self.text length] - 1)];
      else
          self.text = nil;
      [[NSNotificationCenter defaultCenter] postNotificationName:kInputObjectTextDidChangeNotification object:self];
  }
  

假设您想在 -viewDidAppear: 中调用键盘，代码如下:

    - (void)viewDidLoad
    {
        [super viewDidLoad];
        // inputObject and textField are both your ivars in your view controller
        inputObject = [[InputObject alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
        textField = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 100, 30)];
        inputObject.inputAccessoryView = textField;
        [self.view addSubview:inputObject];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(inputObjectTextDidChange:) name:kInputObjectTextDidChangeNotification object:nil];

    }

    - (void)viewDidAppear:(BOOL)animated
    {
        [super viewDidAppear:animated];
        [inputObject becomeFirstResponder]; // This will summon the keyboard
    }

然后在你的 View Controller 中实现通知选择器:

    - (void)inputObjectTextDidChange:(NSNotification *)notification
    {
        // Just set the text here. notification.object is actually your inputObject.
        textField.text = ((InputObject *)(notification.object)).text;
    }

这可能就是您所说的“最初没有 UITextField 的情况下设置 inputAccessoryView”

• 另一种解决方法是通过仔细安排其动画，让文本字段“假装”为 inputAccessoryView。但此解决方案需要您的 textField 成为第一响应者。

首先，您在 -viewDidLoad 中观察键盘事件:

    - (void)viewDidLoad
    {
        [super viewDidLoad];
        // Init the textField and add it as a subview of self.view
        textField = [[UITextField alloc] init];
        textField.backgroundColor = [UIColor redColor];
        [self.view addSubview:textField];

        // Register keyboard events
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShowNotification:) name:UIKeyboardWillShowNotification object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHideNotification:) name:UIKeyboardWillHideNotification object:nil];
    }

其次，在 -viewWillAppear: 中设置您的 textField 的框架，以保证其框架不会受到自动调整的影响:

    - (void)viewWillAppear:(BOOL)animated
    {
        [super viewWillAppear:animated];
        textField.frame = CGRectMake(0, CGRectGetMaxY(self.view.bounds), CGRectGetWidth(self.view.bounds), 50);
    }

然后，安排您的textField 动画，让它与键盘动画同步。您的键盘通知选择器可能是这样的:

    - (void)keyboardWillShowNotification:(NSNotification *)notification
    {
        NSDictionary *userInfo = notification.userInfo;
        UIViewAnimationCurve curve = [[userInfo valueForKey:UIKeyboardAnimationCurveUserInfoKey] intValue];
        CGFloat duration = [[userInfo valueForKey:UIKeyboardAnimationDurationUserInfoKey] floatValue];
        CGRect keyboardFrame = [[userInfo valueForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
        keyboardFrame = [self.view convertRect:keyboardFrame toView:self.view];

        [UIView animateWithDuration:duration delay:0.0f options:(UIViewAnimationOptions)curve animations:^{
            CGRect textFieldFrame = textField.frame;
            textFieldFrame.origin.y = keyboardFrame.origin.y - CGRectGetHeight(textFieldFrame);
            textField.frame = textFieldFrame;
        }completion:nil];
    }

    - (void)keyboardWillHideNotification:(NSNotification *)notification
    {
        NSDictionary *userInfo = notification.userInfo;
        UIViewAnimationCurve curve = [[userInfo valueForKey:UIKeyboardAnimationCurveUserInfoKey] intValue];
        CGFloat duration = [[userInfo valueForKey:UIKeyboardAnimationDurationUserInfoKey] floatValue];
        [UIView animateWithDuration:duration delay:0.0f options:(UIViewAnimationOptions)curve animations:^{
            textField.frame = CGRectMake(0, CGRectGetMaxY(self.view.bounds), CGRectGetWidth(self.view.bounds), 50);
        }completion:nil];
    }

最后调用[textField becomeFirstResponder]触发动画。