Question

我有一个带有分层容器视图的ViewController，以及这个SegmentedController代码：

@IBOutlet weak var dayPicker: UISegmentedControl!

@IBAction func dayPickerControl(sender: UISegmentedControl) {

    switch dayPicker.selectedSegmentIndex {
    case 0:
        monContainer.hidden = false
        tuesContainer.hidden = true
        wedContainer.hidden = true
        thursContainer.hidden = true
        friContainer.hidden = true
        satContainer.hidden = true
        sunContainer.hidden = true
    case 1:
        monContainer.hidden = true
        tuesContainer.hidden = false
        wedContainer.hidden = true
        thursContainer.hidden = true
        friContainer.hidden = true
        satContainer.hidden = true
        sunContainer.hidden = true
    case 2:
        monContainer.hidden = true
        tuesContainer.hidden = true
        wedContainer.hidden = false
        thursContainer.hidden = true
        friContainer.hidden = true
        satContainer.hidden = true
        sunContainer.hidden = true
    case 3:
        monContainer.hidden = true
        tuesContainer.hidden = true
        wedContainer.hidden = true
        thursContainer.hidden = false
        friContainer.hidden = true
        satContainer.hidden = true
        sunContainer.hidden = true
    case 4:
        monContainer.hidden = true
        tuesContainer.hidden = true
        wedContainer.hidden = true
        thursContainer.hidden = true
        friContainer.hidden = false
        satContainer.hidden = true
        sunContainer.hidden = true
    case 5:
        monContainer.hidden = true
        tuesContainer.hidden = true
        wedContainer.hidden = true
        thursContainer.hidden = true
        friContainer.hidden = true
        satContainer.hidden = false
        sunContainer.hidden = true
    case 6:
        monContainer.hidden = true
        tuesContainer.hidden = true
        wedContainer.hidden = true
        thursContainer.hidden = true
        friContainer.hidden = true
        satContainer.hidden = true
        sunContainer.hidden = false
    default:
        break;
    }

如何从另一个视图控制器中选择某个片段，以便当我返回到此视图时，可以看到我想要的容器并选择相应的片段？

Answer 1

首先，您需要将某个地方的全局状态保存到应用程序的任何部分才能访问。即使像共享对象（单例）或绑定到UIApplicationDelegate的对象这样简单的东西也可以在这里完成。

一种选择是使用单例方法。很多人不喜欢出于各种原因使用单身人士，但我认为在这种情况下，这很容易说明全球价值。单例的关键是在应用程序的生命周期内保持一个对象。另一种方法是将此状态与UIApplicationDelegate联系起来。

要实现单例（如果你愿意，你可以将它放在自己的文件中，我称之为UserState，但你可以将其改为你想要的任何内容）：

private let _UserStateSharedInstance = UserState()

class UserState  {
    class var sharedInstance : UserState {
        return _UserStateSharedInstance
    }
    var selectedDay = 0
}

在此视图控制器中，您可以检索所选日期：

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    dayPicker.selectedSegmentIndex = UserState.sharedInstance.selectedDay
}

@IBAction func dayPickerControl(sender: UISegmentedControl) {
    UserState.sharedInstance.selectedDay = sender.selectedSegmentIndex // You probably also want to set this here

    // Do your switching here
}

在其他视图控制器中，您可以设置所选日期：

@IBAction func dayPickerControl(sender: UISegmentedControl) {
    UserState.sharedInstance.selectedDay = sender.selectedSegmentIndex
}

虽然我们正在努力，但我可以建议一种更简单的方法来进行此转换吗？

我们可以将每个案例组合成一个简单的逻辑语句，以避免不得不一遍又一遍地重复列表：

@IBAction func dayPickerControl(sender: UISegmentedControl) {

    let segmentIndex = sender.selectedSegmentIndex

    monContainer.hidden = (segmentIndex != 0)
    tuesContainer.hidden = (segmentIndex != 1)
    wedContainer.hidden = (segmentIndex != 2)
    thursContainer.hidden = (segmentIndex != 3)
    friContainer.hidden = (segmentIndex != 4)
    satContainer.hidden = (segmentIndex != 5)
    sunContainer.hidden = (segmentIndex != 6)
}

现在它变得越来越明显，这只是我们想要根据索引隐藏/显示的一系列视图。我们可以用循环重写它：

var viewsToHide: [UIView]?

override func viewDidLoad() {
    super.viewDidLoad()

    viewsToHide = [monContainer, tuesContainer, wedContainer, thursContainer, friContainer, satContainer, sunContainer]
}

@IBAction func dayPickerControl(sender: UISegmentedControl) {

    let segmentIndex = sender.selectedSegmentIndex

    for (index, view) in enumerate(viewsToHide ?? []) {
        view.hidden = (segmentIndex != index)
    }
}

在视图控制器之外选择UISegmentedController段

1 个答案: