当键盘出现时，我如何让 UITextField 向上移动？

Question

With the iOS SDK:

I have a UIView with UITextFields that bring up a keyboard. I need it to be able to:

1. Allow scrolling of the contents of the UIScrollView to see the other text fields once the keyboard is brought up

2. Automatically "jump" (by scrolling up) or shortening

I know that I need a UIScrollView. I've tried changing the class of my UIView to a UIScrollView but I'm still unable to scroll the textboxes up or down.

Do I need both a UIView and a UIScrollView? Does one go inside the other?

What needs to be implemented in order to automatically scroll to the active text field?

Ideally as much of the setup of the components as possible will be done in Interface Builder. I'd like to only write code for what needs it.

Note: the UIView (or UIScrollView) that I'm working with is brought up by a tabbar (UITabBar), which needs to function as normal.

---

Edit: I am adding the scroll bar just for when the keyboard comes up. Even though it's not needed, I feel like it provides a better interface because then the user can scroll and change textboxes, for example.

I've got it working where I change the frame size of the UIScrollView when the keyboard goes up and down. I'm simply using:

-(void)textFieldDidBeginEditing:(UITextField *)textField { 
    //Keyboard becomes visible
    scrollView.frame = CGRectMake(scrollView.frame.origin.x, 
                     scrollView.frame.origin.y, 
scrollView.frame.size.width,
scrollView.frame.size.height - 215 + 50);   //resize
}

-(void)textFieldDidEndEditing:(UITextField *)textField {
   //keyboard will hide
    scrollView.frame = CGRectMake(scrollView.frame.origin.x, 
       scrollView.frame.origin.y, 
     scrollView.frame.size.width,
      scrollView.frame.size.height + 215 - 50); //resize
}

However, this doesn't automatically "move up" or center the lower text fields in the visible area, which is what I would really like.

转载于:https://stackoverflow.com/questions/1126726/how-can-i-make-a-uitextfield-move-up-when-the-keyboard-is-present

Answer 1

1. You will only need a ScrollView if the contents you have now do not fit in the iPhone screen. (If you are adding the ScrollView as the superview of the components. just to make the TextField scroll up when keyboard comes up, then it's not needed.)

2. For showing the textfields without being hidden by the keyboard, the standard way is to move up/down the view having textfields whenever the keyboard is shown.

Here is some sample code:

#define kOFFSET_FOR_KEYBOARD 80.0

-(void)keyboardWillShow {
    // Animate the current view out of the way
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)keyboardWillHide {
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)textFieldDidBeginEditing:(UITextField *)sender
{
    if ([sender isEqual:mailTf])
    {
        //move the main view, so that the keyboard does not hide it.
        if  (self.view.frame.origin.y >= 0)
        {
            [self setViewMovedUp:YES];
        }
    }
}

//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view

    CGRect rect = self.view.frame;
    if (movedUp)
    {
        // 1. move the view's origin up so that the text field that will be hidden come above the keyboard 
        // 2. increase the size of the view so that the area behind the keyboard is covered up.
        rect.origin.y -= kOFFSET_FOR_KEYBOARD;
        rect.size.height += kOFFSET_FOR_KEYBOARD;
    }
    else
    {
        // revert back to the normal state.
        rect.origin.y += kOFFSET_FOR_KEYBOARD;
        rect.size.height -= kOFFSET_FOR_KEYBOARD;
    }
    self.view.frame = rect;

    [UIView commitAnimations];
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    // register for keyboard notifications
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

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

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    // unregister for keyboard notifications while not visible.
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}