NSFetchRequest Core Data Swift 3向后兼容性 [英] NSFetchRequest Core Data Swift 3 Backward compatibility

问题描述

我已经转换我的代码在swift 3.我在我的应用程序中使用核心数据。如你所知，NSFetchRequest已更改。
在swift 2中是：

I have converted my code in swift 3. I am using core data in my application. As you know, NSFetchRequest has been changed. In swift 2 it was:

let request = NSFetchRequest(entityName: "UnsyncedTask")

在swift 3中：

let request:NSFetchRequest<NSFetchRequestResult> = UnsyncedTask.fetchRequest()

我的问题是，它只支持ios 10.如何使向后兼容ios？
我想要NSFetchRequest它支持ios 9，ios 10与swift 3.

My question is, It only supports ios 10. How can I make it backward ios compatible? I want NSFetchRequest which supports ios 9, ios 10 with swift 3.

推荐答案

NSFetchRequest （entityName：）在Swift 3中仍然可用。
如果#available 在iOS 10/10上使用较新的API，您可以使用 macOS 10.12
或更高版本，旧操作系统版本上的旧API：

NSFetchRequest(entityName:) is still available in Swift 3. You can use if #available to use the newer API on iOS 10/macOS 10.12 or later, and the older API on older OS versions:

let request: NSFetchRequest<UnsyncedTask>
if #available(iOS 10.0, OSX 10.12, *) {
    request = UnsyncedTask.fetchRequest()
} else {
    request = NSFetchRequest(entityName: "UnsyncedTask")
}
do {
    let results = try context.fetch(request)
    for task in results {
        // ...
    }
} catch let error {
    print(error.localizedDescription)
}

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