在键盘顶部显示文本视图时改进动画

Question

当UIKeyboardWillShowNotification 像下面这样广播时，我正在制作动画以在顶部键盘上显示文本视图

-(void) keyboardWillShow:(NSNotification *)notification{
    // get keyboard size and loctaion
    NSDictionary *info = [notification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    NSNumber *duration = [notification.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];

    __block CGRect containerFrame = containerView.frame;

    containerFrame.origin.y = self.view.bounds.size.height - (kbSize.height + containerFrame.size.height);
    [UIView animateWithDuration:[duration doubleValue]
                          delay:0
                        options:UIViewAnimationOptionBeginFromCurrentState
                     animations:^{
                         containerView.frame = containerFrame;
                     } completion:^(BOOL finished) {
                         nil;
                     }
     ];
}

动画不够好。如果您可以尝试一下，并且在动画结束时会看到小问题。

我搜索了一下，发现还有另一种制作动画的方法，而且效果很好：

-(void) keyboardWillShow:(NSNotification *)note{
    // get keyboard size and loctaion
    CGRect keyboardBounds;
    [[note.userInfo valueForKey:UIKeyboardFrameEndUserInfoKey] getValue: &keyboardBounds];
    NSNumber *duration = [note.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    NSNumber *curve = [note.userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey];

    // Need to translate the bounds to account for rotation.
    keyboardBounds = [self.view convertRect:keyboardBounds toView:nil];

    // get a rect for the textView frame
    CGRect containerFrame = containerView.frame;
    containerFrame.origin.y = self.view.bounds.size.height - (keyboardBounds.size.height + containerFrame.size.height);
    // animations settings
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:[duration doubleValue]];
    [UIView setAnimationCurve:[curve intValue]];

    // set views with new info
    containerView.frame = containerFrame;


    // commit animations
    [UIView commitAnimations];
}

但是，根据文档，我们不建议在 iOS 4 及更高版本中使用此动画...

与后一种代码相比，我无法区分我的代码。为什么我的代码不能做完美的动画。如果您有任何想法，请提供帮助。

Answer 1

这是动画曲线。您引用的示例是将其动画曲线及其持续时间与键盘的动画曲线相匹配。你的代码没有。你的结构应该更像这样：

NSNumber* curve = info[UIKeyboardAnimationCurveUserInfoKey]; // *
NSNumber* duration = info[UIKeyboardAnimationDurationUserInfoKey];
[UIView animateWithDuration:duration.floatValue delay:0
                    options:curve.integerValue << 16 // *
                 animations: ^{ // ...