Swift可用性检查不包括macOS

由 发布于 iosmacosswiftconditional-compilation
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我的应用程序中有一个代码，希望在iOS 13或更高版本上执行。因此，我正在使用标准的可用性检查：

if #available(iOS 13.0, *) {
    return Color.systemGray6.resolvedColor(with: trait!)
} else {
    return Color(red: 0.082, green: 0.118, blue: 0.161, alpha: 1.0)
}

Color is a typealias which casts to UIColor on iOS and NSColor on macOS. I am kind of trying to create macOS version of my target with as little if..else as possible.

The code above should work as NSColor has many of the same init methods as UIColor. The problem is that when I build my macOS target it complains about systemGray6. So, for a reason unknown to me, macOS target passes #available(iOS 13.0, *) check!

为什么会发生，如何预防呢？

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Alex55
Alex55

When you use if #available(iOS 13.0, *) you're basically saying: do this on iOS 13.0 and later, and on all other operating systems - that's what the * means.

In your specific case, you'll need to exclude macOS, since NSColor does not have the systemGrayX getters:

#if os(iOS)
if #available(iOS 13.0, *) {
     return Color.systemGray6
}
#endif
return Color(red: 0.082, green: 0.118, blue: 0.161, alpha: 1.0)
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