1

在我的应用程序中，我有这个错误 -

safeAreaLayoutGuide' is only available on iOS 11.0 or newer

在此代码中，错误出现 3 次。基本上在我使用 safeArea 的每一行中。

NSLayoutConstraint.activate([
        stackViewBottomConstrols.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
        stackViewBottomConstrols.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
        stackViewBottomConstrols.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
        stackViewBottomConstrols.heightAnchor.constraint(equalToConstant: 50)
        ])

我可以检查是否IOS 11可用并运行此代码并在else语句中添加另一个具有相同代码但没有安全区域的代码。这是否会显示与声明中相同的视图if。如果没有，还有其他解决方案吗？

此代码是否可以在没有 IOS 11 的设备上运行？-

        if #available(iOS 11.0, *) {
        NSLayoutConstraint.activate([
            stackViewBottomConstrols.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
            stackViewBottomConstrols.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
            stackViewBottomConstrols.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
            stackViewBottomConstrols.heightAnchor.constraint(equalToConstant: 50)
            ])
    } else {
        NSLayoutConstraint.activate([
            stackViewBottomConstrols.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            stackViewBottomConstrols.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            stackViewBottomConstrols.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            stackViewBottomConstrols.heightAnchor.constraint(equalToConstant: 50)
            ])
    }
4

2 回答 2

5

safeAreaLayoutGuide is just a replacement for top,bottom layout guides with addition of leading , trailing - of course your'code is good to go and this is the only way to create constraints in code to support IOS 11 and lower versions , but only to switch for constraints that matter not this

stackViewBottomConstrols.heightAnchor.constraint(equalToConstant: 50)

to be this

if #available(iOS 11.0, *) {
    NSLayoutConstraint.activate([
        stackViewBottomConstrols.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
        stackViewBottomConstrols.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
        stackViewBottomConstrols.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor)
     ])
} else {
    NSLayoutConstraint.activate([
        stackViewBottomConstrols.bottomAnchor.constraint(equalTo: self.bottomLayoutGuide.topAnchor),
        stackViewBottomConstrols.leadingAnchor.constraint(equalTo: view.leadingAnchor),
        stackViewBottomConstrols.trailingAnchor.constraint(equalTo: view.trailingAnchor)
     ])
      
}
于 2018-01-22T21:07:34.120 回答
0

If you want to be as consistent as possible, in the pre-iOS-11 block, replace view.bottomAnchor with bottomLayoutGuide.topAnchor. Prior to iOS 11, there are still topLayoutGuide and bottomLayoutGuide to help the programmer factor in nav bars, tab bars, etc. Otherwise, looks good to me!

Edit: resulting code:

if #available(iOS 11.0, *) {
    NSLayoutConstraint.activate([
        stackViewBottomConstrols.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
        stackViewBottomConstrols.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
        stackViewBottomConstrols.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
        ])
} else {
    NSLayoutConstraint.activate([
        stackViewBottomConstrols.bottomAnchor.constraint(equalTo: bottomLayoutGuide.topAnchor),
        stackViewBottomConstrols.leadingAnchor.constraint(equalTo: view.leadingAnchor),
        stackViewBottomConstrols.trailingAnchor.constraint(equalTo: view.trailingAnchor),
        ])
}
// This one doesn't care which iOS version it is
stackViewBottomConstrols.heightAnchor.constraint(equalToConstant: 50)
于 2018-01-22T21:11:10.947 回答