iOS 查看能见度消失

Question

我是 iOS 的新手 development.I 想切换 (hide/visible) 来自父视图的子视图 view.In android 有一种方法可以隐藏能见度消失。

在android

subView.setVisibility(View.GONE);

在iOS

subView.removeFromSuperview()

当我使用上面的函数时，它删除了 subViewConstraints 并弄乱了我的滚动视图约束。

topsubView.bottomAnchor.constraint(equalTo: bottomSubView.topAnchor, constant: 8).isActive = true

当我使用上面的代码时，它工作正常并隐藏 subView.but 当我想让子视图可见时，它没有显示子视图。

topsubView.bottomAnchor.constraint(equalTo: bottomSubView.topAnchor, constant: 8).isActive = false
self.view.layoutIfNeeded()

希望你提前理解我的problem.Thanks。

Answer 1

我相信您正在寻找 view.isHidden = true。这只是在不改变视图层次结构或约束映射的情况下将视图隐藏到位。您随后可以重新显示您的视图。 view.isHidden = false.

Answer 2

因为我在 iOS 和 Android 上都工作过，所以您需要在 ios 中使用约束插座来实现 Android 功能。 iOS 不支持自动像 Android 原生支持可见性 GONE & VISIBLE

您需要挂钩特定 constraint 的 outlet（可能 vertical/horizontal/height）您需要将其设置为 0 并且需要管理您的 UI.

隐藏：

self.viewYourConstraint.constant = 0
self.yourView.hidden = true
self.view.layoutIfNeeded()

显示：

self.viewYourConstraint.constant = 100//your constant value
self.yourView.hidden = false
self.view.layoutIfNeeded()

Note: If other constraints will be affected because of the update to the constraint above, the following must also need to be called:

self.yourView.setNeedsUpdateConstraints()

Answer 3

你说你想隐藏你的子视图并删除它占用的space。如果你想避免搞乱约束，你可以尝试使用堆栈视图：

创建 UIStackView 并在堆栈视图及其父视图之间设置适当的约束；
将视图添加到堆栈视图；
现在您可以通过将 view.isHidden 设置为 true 或 false 来切换这些视图在堆栈视图中的可见性，布局将自动调整。

Answer 4

试试这个扩展：

extension UIView {
    
    func visiblity(gone: Bool, dimension: CGFloat = 0.0, attribute: NSLayoutAttribute = .height) -> Void {
        if let constraint = (self.constraints.filter{[=10=].firstAttribute == attribute}.first) {
            constraint.constant = gone ? 0.0 : dimension
            self.layoutIfNeeded()
            self.isHidden = gone
        }
    }
}

如何使用它....

@IBOutlet weak var testView: UIView?
@IBAction func testVisibilty(switchbutton: UISwitch) -> Void {
    
    let viewHeight:CGFloat = switchbutton.isOn ? 100 : 0.0
    self.testView?.visiblity(gone: !switchbutton.isOn, dimension: viewHeight)
    
    // set visibility for width constraint
    //let viewWidth:CGFloat = switchbutton.isOn ? 300 : 0.0
    //self.testView?.visiblity(gone: !switchbutton.isOn, dimension: viewWidth, attribute: .width)
  
}

这是结果：

Answer 5

也许您更喜欢这个解决方案

extension UIView {

    enum Visibility {
        case visible
        case invisible
        case gone
    }

    var visibility: Visibility {
        get {
            let constraint = (self.constraints.filter{[=10=].firstAttribute == .height && [=10=].constant == 0}.first)
            if let constraint = constraint, constraint.isActive {
                return .gone
            } else {
                return self.isHidden ? .invisible : .visible
            }
        }
        set {
            if self.visibility != newValue {
                self.setVisibility(newValue)
            }
        }
    }

    private func setVisibility(_ visibility: Visibility) {
        let constraint = (self.constraints.filter{[=10=].firstAttribute == .height && [=10=].constant == 0}.first)

        switch visibility {
        case .visible:
            constraint?.isActive = false
            self.isHidden = false
            break
        case .invisible:
            constraint?.isActive = false
            self.isHidden = true
            break
        case .gone:
            if let constraint = constraint {
                constraint.isActive = true
            } else {
                let constraint = NSLayoutConstraint(item: self, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1, constant: 0)
                self.addConstraint(constraint)
                constraint.isActive = true
            }
        }
    }
}

那么用法是：

someView.visibility = .visible
someView.visibility = .invisible
someView.visibility = .gone

编辑：

提高能力：将在 "Visibility State"

中从故事板开始工作（只需写：'visible'、'invisible'、'gone'）

视图内的所有约束都应小于 1000

extension UIView {

    enum Visibility: String {
        case visible = "visible"
        case invisible = "invisible"
        case gone = "gone"
    }

    var visibility: Visibility {
        get {
            let constraint = (self.constraints.filter{[=12=].firstAttribute == .height && [=12=].constant == 0}.first)
            if let constraint = constraint, constraint.isActive {
                return .gone
            } else {
                return self.isHidden ? .invisible : .visible
            }
        }
        set {
            if self.visibility != newValue {
                self.setVisibility(newValue)
            }
        }
    }

    @IBInspectable
    var visibilityState: String {
        get {
            return self.visibility.rawValue
        }
        set {
            let _visibility = Visibility(rawValue: newValue)!
            self.visibility = _visibility
        }
    }

    private func setVisibility(_ visibility: Visibility) {
        let constraints = self.constraints.filter({[=12=].firstAttribute == .height && [=12=].constant == 0 && [=12=].secondItem == nil && ([=12=].firstItem as? UIView) == self})
        let constraint = (constraints.first)

        switch visibility {
        case .visible:
            constraint?.isActive = false
            self.isHidden = false
            break
        case .invisible:
            constraint?.isActive = false
            self.isHidden = true
            break
        case .gone:
            self.isHidden = true
            if let constraint = constraint {
                constraint.isActive = true
            } else {
                let constraint = NSLayoutConstraint(item: self, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1, constant: 0)
                // constraint.priority = UILayoutPriority(rawValue: 999)
                self.addConstraint(constraint)
                constraint.isActive = true
            }
            self.setNeedsLayout()
            self.setNeedsUpdateConstraints()
        }
    }
}

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