UIPickerView 高度约束动画跳跃

Question

我正在为 UIPickerView 的高度约束设置动画。 视图跳到一个小的高度仍然显示 1 行，然后动画直到高度 0。

UIView.animate(withDuration: 0.5, animations: {
        self.timePickerHeightConstraint.constant =    self.pickerIsClosed ? 216 : 0
        self.view.layoutIfNeeded()
    }) { compilation in
        self.pickerIsClosed = !self.pickerIsClosed
    }

有什么建议吗？ 谢谢

Answer 1

试试这样的，

func showPickerView(_ animated: Bool) {
    weak var weakSelf = self
    UIView.animate(withDuration: (animated ? kPickerView_AppearanceAnimationDuration : 0.0), delay: (animated ? kPickerView_AppearanceAnimationDelay : 0.0), options: (animations as! UIViewAnimationOptionCurveEaseInOut), {() -> Void in
        weakSelf!.pickerViewContainerView.transform = CGAffineTransform(translationX: 0, y: 0)
    }, completion: {(finished: Bool) -> Void in
        weakSelf!.view.layoutIfNeeded()
    })
}

func hidePickerView(_ animated: Bool) {
    weak var weakSelf = self
    UIView.animate(withDuration: (animated ? kPickerView_DisappearanceAnimationDuration : 0.0), delay: (animated ? kPickerView_DisappearanceAnimationDelay : 0.0), options: (animations as! UIViewAnimationOptionCurveEaseInOut), {() -> Void in
        weakSelf!.pickerViewContainerView.transform = CGAffineTransform(translationX: 0, y: kPickerView_Height)
    }, completion: {(finished: Bool) -> Void in

它对我有用。

Answer 2

您应该在动画块之外更改约束常量值，

self.timePickerHeightConstraint.constant =    self.pickerIsClosed ? 216 : 0

UIView.animate(withDuration: 0.5, animations: {
    self.view.layoutIfNeeded()
}) { compilation in
    self.pickerIsClosed = !self.pickerIsClosed
}

另外请确保您没有设置顶部和底部约束，因为这将不允许自动布局将高度设置为 0 点。

Answer 3

我遇到了同样的问题。似乎 UIPickerView 的高度动画效果不佳，或者至少按照我希望的方式进行动画处理。

我发现的解决方法是将 UIPickerView 包装在 UIView 中，将 UIView 的 clipsToBounds 设置为 true，然后在 UIView 包装器的高度约束上执行动画，而不是直接使用 UIPickerView。需要注意的一点是，要使其正常工作，UIPicker 视图的高度必须独立于包装器视图的高度进行约束，否则它的反应方式与没有包装器时相同。

 // create and add UIPicker to view
    UIPickerView *picker = [[UIPickerView alloc] init];
    picker.translatesAutoresizingMaskIntoConstraints = NO;
    picker.delegate = self;
    picker.dataSource = self;
    picker.alpha = 0.0;
    _myUiPicker = picker; // weak reference property

    // make wrapper view
    UIView *wrapper = [UIView new];
    wrapper.translatesAutoresizingMaskIntoConstraints = NO;
    wrapper.clipsToBounds = YES;
    [wrapper addSubview:picker];
    [self.view addSubview:wrapper];

    // Picker constraints
    [picker.leadingAnchor constraintEqualToAnchor:wrapper.leadingAnchor].active = YES;
    [picker.trailingAnchor constraintEqualToAnchor:wrapper.trailingAnchor].active = YES;

    // ***** Note this height is not determined by wrapper view ***
    [picker.heightAnchor constraintEqualToConstant:130.0].active = YES;
    // ****
    [picker.topAnchor constraintEqualToAnchor:wrapper.topAnchor].active = YES;

    // wrapper constraints
    [wrapper.leadingAnchor constraintEqualToAnchor:self.view.leadingAnchor].active = YES;
    [wrapper.trailingAnchor constraintEqualToAnchor:self.view.trailingAnchor].active = YES;
    // **** this is the constraint you will animate ***
    NSLayoutConstraint *heightConstraint = [wrapper.heightAnchor constraintEqualToConstant:0.0];
    heightConstraint.active = YES;
    // ****
    NSLayoutConstraint *topConstraint = [wrapper.topAnchor constraintEqualToAnchor:self.view.topAnchor constant:8.0];
    topConstraint.active = YES;
    [self.view layoutIfNeeded]; // initial layout

    // animate picker height and reminderBtn position
    [UIView animateWithDuration:JAPPickerAnimationTime animations:^{
        heightConstraint.constant = 130.0; // from 0 to 130
        picker.alpha = 1.0; // make is show
        [self.view layoutIfNeeded];
    }];

Answer 4

选择器组件行的高度是多少。签到

func pickerView(pickerView: UIPickerView, rowHeightForComponent 组件: Int)

当 self.pickerIsClosed == true 时返回 0。