问将UIView沿键盘显示为动画

EN

@implementation TSViewController
{
    IBOutlet UIToolbar*     _toolbar; // parented in your view somewhere

    IBOutlet UITextField*   _textField; // the customView of a UIBarButtonItem in the toolbar

    IBOutlet UIToolbar*     _inputAccessoryToolbar; // not parented.  just owned by the view controller.

    IBOutlet UITextField*   _inputAccessoryTextField; // the customView of a UIBarButtonItem in the inputAccessoryToolbar
}

- (void) viewDidLoad
{
    [super viewDidLoad];

    _textField.delegate = self;
    _inputAccessoryTextField.delegate = self;

    _textField.inputAccessoryView = _inputAccessoryToolbar;
}

- (void) textFieldDidBeginEditing: (UITextField *) textField
{
    if ( textField == _textField )
    {
        // can't change responder directly during textFieldDidBeginEditing.  postpone:
        dispatch_async(dispatch_get_main_queue(), ^{

            _inputAccessoryTextField.text = textField.text;

            [_inputAccessoryTextField becomeFirstResponder];
        });
    }
}

- (BOOL) textFieldShouldBeginEditing: (UITextField *) textField
{
    if ( textField == _textField )
    {
        // only become first responder if the inputAccessoryTextField isn't the first responder.
        return ![_inputAccessoryTextField isFirstResponder];
    }
    return YES;
}

- (void) textFieldDidEndEditing: (UITextField *) textField
{
    if ( textField == _inputAccessoryTextField )
    {
        _textField.text = textField.text;
    }
}

// invoke this when you want to dismiss the keyboard!
- (IBAction) done: (id) sender
{
    [_inputAccessoryTextField resignFirstResponder];
}

@end

@implementation TSViewController
{
    IBOutlet UITextField*           _textField;

    IBOutlet UIToolbar*             _toolbar;

    IBOutlet NSLayoutConstraint*    _toolbarBottomDistanceConstraint;

    CADisplayLink*                  _displayLink;
}

- (void) dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver: self];
}

- (void) viewDidLoad
{
    [super viewDidLoad];

    [self.view addGestureRecognizer: [[UITapGestureRecognizer alloc] initWithTarget: self action: @selector( dismiss:) ]];

    _textField.inputAccessoryView = [[UIView alloc] init];

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

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

    [[NSNotificationCenter defaultCenter] addObserver: self
                                             selector: @selector(keyboardDidShowHide:)
                                                 name: UIKeyboardDidShowNotification
                                               object: nil];

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

- (void) keyboardWillShowHide: (NSNotification*) n
{
    _displayLink = [CADisplayLink displayLinkWithTarget: self selector:  @selector( tick: )];
    [_displayLink addToRunLoop: [NSRunLoop currentRunLoop] forMode: NSRunLoopCommonModes];
}

- (void) keyboardDidShowHide: (NSNotification*) n
{
    [_displayLink removeFromRunLoop: [NSRunLoop currentRunLoop] forMode: NSRunLoopCommonModes];
}

- (void) tick: (CADisplayLink*) dl
{
    CGRect r = [_textField.inputAccessoryView.superview.layer.presentationLayer frame];
    r = [self.view convertRect: r fromView: _textField.inputAccessoryView.superview.superview];

    CGFloat fromBottom = self.view.bounds.size.height - r.origin.y;
    _toolbarBottomDistanceConstraint.constant = fromBottom;
}

- (IBAction) dismiss: (id) sender
{
    [self.view endEditing: YES];
}

@end