Synchronizing Animations in keyboardWillShow keyboardWillHide — Hardware Keyboard & Virtual Keyboard Simultaneously

问题

Preamble

So I have an application featuring a chat section, and I'm synchronizing the animation of the keyboard hiding and showing with the rise and fall of the chat input.

Here's the code I'm using:

SHOW:

- (void) keyboardWillShow:(NSNotification *)note {

    NSDictionary *keyboardAnimationDetail = [note userInfo];
    UIViewAnimationCurve animationCurve = [keyboardAnimationDetail[UIKeyboardAnimationCurveUserInfoKey] integerValue];
    CGFloat duration = [keyboardAnimationDetail[UIKeyboardAnimationDurationUserInfoKey] floatValue];

    NSValue* keyboardFrameBegin = [keyboardAnimationDetail valueForKey:UIKeyboardFrameBeginUserInfoKey];
    CGRect keyboardFrameBeginRect = [keyboardFrameBegin CGRectValue];

    // working for hardware keyboard
    //UIViewAnimationOptions options = (UIViewAnimationOptions)animationCurve;

    // working for virtual keyboard
    UIViewAnimationOptions options = (animationCurve << 16);

    [UIView animateWithDuration:duration delay:0.0 options:options animations:^{
        textView.frame = CGRectMake(0, self.view.bounds.size.height - keyboardFrameBeginRect.size.height, self.view.bounds.size.width, -40);
    } completion:nil];

}

HIDE:

- (void) keyboardWillHide:(NSNotification *)note {

    NSDictionary *keyboardAnimationDetail = [note userInfo];
    UIViewAnimationCurve animationCurve = [keyboardAnimationDetail[UIKeyboardAnimationCurveUserInfoKey] integerValue];
    CGFloat duration = [keyboardAnimationDetail[UIKeyboardAnimationDurationUserInfoKey] floatValue];

    // hardware keyboard
    //UIViewAnimationOptions options = (UIViewAnimationOptions)animationCurve;

    // virtual keyboard
    UIViewAnimationOptions options = (animationCurve << 16);

    [UIView animateWithDuration:duration delay:0.0 options:options animations:^{
        textView.frame = CGRectMake(0, self.view.bounds.size.height, self.view.bounds.size.width, -40);
    } completion:nil];

}

This works great with the virtual keyboard, but if keyboardWillShow: or keyboardWillHide: is called as a result of disconnecting or connecting a hardware keyboard, the animation lags. I can fix this by changing the UIViewAnimationOptions

Replace:

// Works with virtual keyboard
UIViewAnimationOptions options = (animationCurve << 16);

With:

// working for firstResponder keyboard
UIViewAnimationOptions options = (UIViewAnimationOptions)animationCurve;

But with this, now the virtualKeyboard animation lags

I realize that hardware keyboard animations aren't very common and it's perhaps not the most important issue, but I like everything to just work!

Examples

VirtualKeyboard w/ (animationCurve << 16) -- WORKING

VirtualKeyboard w/ (UIViewAnimationOptions)animationCurve -- BROKEN

HardwareKeyboard w/ (animationCurve << 16) -- BROKEN

HardwareKeyboard w/ (UIViewAnimationOptions)animationCurve -- WORKING

Notes

To simulate hardware keyboard in simulator cmd + shft + k

Yes, this is replicable on real device.

In case you want it, here's the rest of my code, just for replication purposes

ADD TEXT VIEW

textView = [UITextView new];
textView.layer.borderWidth = 10;
textView.layer.borderColor = [UIColor blackColor].CGColor;
textView.frame = CGRectMake(0, self.view.bounds.size.height, self.view.bounds.size.width, -40);
[self.view addSubview:textView];

UITapGestureRecognizer * tap = [[UITapGestureRecognizer alloc]init];
[tap addTarget:self action:@selector(handleTap:)];
[self.view addGestureRecognizer:tap];

// OBSERVE KEYBOARD
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow:)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide:)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];

HANDLE TAP:

- (void) handleTap:(UITapGestureRecognizer *)tap {
    NSLog(@"tapped");
    [textView resignFirstResponder];
}

The Question:

What is going on here, and is there a good way to get consistent animation regardless of virtual / hardware keyboard?

I realize this is long, thank you for reading!

回答1:

Since the animation curve Apple sends you in the keyboard notification does not have a corresponding UIViewAnimationOption bit, you need to drop down to old-school non-block animations and use the curve directly:

NSTimeInterval duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
UIViewAnimationCurve curve = [note.userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue];
[UIView beginAnimations:@"SomeAnimationID" context:NULL];
[UIView setAnimationCurve:curve];
[UIView setAnimationDuration:duration];
// Animation code
[UIView commitAnimations];

回答2:

keyboardWillShow:

NSDictionary *info = [notification userInfo];
CGRect keyboardFrame = [info[UIKeyboardFrameEndUserInfoKey] CGRectValue];
NSTimeInterval duration = [info[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
UIViewAnimationCurve curve = [info[UIKeyboardAnimationCurveUserInfoKey] integerValue];

[self layoutIfNeeded];
[UIView animateWithDuration:duration delay:0 options:(curve << 20) animations:^{
    [self.keyboardConstraint setConstant:keyboardFrame.size.height];
    [self layoutIfNeeded];
} completion:nil];

来源：https://stackoverflow.com/questions/22260711/synchronizing-animations-in-keyboardwillshow-keyboardwillhide-hardware-keyboa