UIStackView 隐藏/取消隐藏排列子视图问题 [英] UIStackView Hiding/UnHiding arrangedSubView issue

问题描述

我正在隐藏和取消隐藏 dropDownView(由文本字段和按钮组成的 UIView)基于在 Segment Control 中点击的 Segment.以下是视图层次结构:-

I am hiding and unhiding dropDownView(UIView consisting of textfield and button) based on Segment tapped in Segment Control. Following is the view hierarchy :-

以下是隐藏/取消隐藏 dropDownView 的代码:-

Following is the code which hides/unhides dropDownView :-

 private func animateView(view: UIStackView, toHidden hidden: Bool) {
    UIView.animate(withDuration: 0.25) 
    {
    let firstView = view.arrangedSubviews[0]
    firstView.isHidden = hidden
    }
    }
func segmentValueChanged(_ sender: UISegmentedControl) {
        let segmentSelected = segmentControl.selectedSegmentIndex
        switch segmentSelected {
        case 0:
            animateView(view: mainStackView, toHidden: true)
        case 1:
         animateView(view: mainStackView, toHidden: true)
        case 2:
            animateView(view: mainStackView, toHidden: true)
        case 3:
           animateView(view: mainStackView, toHidden: false)
        default:
            break
        }
    }

我面临的问题是在更改段超过 10-15 次后，上述代码停止工作并且下拉视图与段控制重叠，我不知道为什么.感谢您对理解此问题的任何帮助.

Problem which I am facing is after changing segments over 10-15 times the above code stops working and DropDown View overlaps with Segment Control and I am not sure why. Any help to understand this issue is appreciated.

我也试过了
<强>1.setNeedsLayout,
2.设置NeedsDisplay和
3. 将 dropDownView 的高度约束的优先级从 999 降低到1000

推荐答案

似乎在 completionClosure 中的附加设置 isHidden 修复了该问题(Swift 5 语法):

Seem the additional setting isHidden in completionClosure fixes that issue (Swift 5 syntax):

private func animateView(view: UIStackView, toHidden hidden: Bool) {
    let firstView = view.arrangedSubviews[0]
    UIView.animate(withDuration: 0.25) {
        firstView.isHidden = hidden
        view.layoutIfNeeded()
    } completion {
        firstView.isHidden = hidden
    }
}

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