Question

我有一个包含对象的类，为了使用该对象的属性，NSURLSession必须完成其异步数据请求。如何通过对象创建回调以了解该功能何时完成，我可以调用这些属性。

Answer 1

你没有给出代码的例子，所以我将在摘要中写。您需要在NSURLSession对象的完成内调用与您的对象一起使用的方法。例如，它可能如下所示：

// This is your object
struct SomeData {
        var someValue: Int = 0
    }

// This is class that use it
class Foo {
    var someData: SomeData

    init() {
        someData = SomeData()
        requestData()
    }

    // This is your function that need to wait for the request
    func doActionWithData() {
        print(someData.someValue)
    }

    // This is request
    func requestData() {
        // Make request with your params
        let request = NSMutableURLRequest(...)
        ...
        // For example you do it like this
        NSURLSession.sharedSession().dataTaskWithRequest(request, completionHandler: { (data, response, error) in
            // here you have data for your object you can get it from 
            // response and then call function to work with it
            self.someData.someValue = ...
            self.doActionWithData()
        })
    }
}

如何在对象内部知道异步函数何时完成？

1 个答案: