Swift Cast AnyObject to Block [英] Swift Cast AnyObject to Block

问题描述

所以我使用的是Salesforce SDK，并为整个SDK建立了桥接头。

So I am using the Salesforce SDK and built bridging headers for the entire SDK.

它们提供了一个块语法，但没有翻译成最可用的代码。例如，

They provide a block syntax which hasn't translated into the most usable code. For instance,

func sendRESTRequest(request: SFRestRequest!, failBlock: SFRestFailBlock!, completeBlock: AnyObject!)

完整的块是AnyObject！我可以用

The complete block is AnyObject!. I was able to get around this with

var block : @objc_block (dataResponse :AnyObject!) -> Void = { dataResponse in //I handle the response}
restService.sendRESTRequest(request, failBlock: { (error :NSError!) -> Void in

        }, completeBlock: unsafeBitCast(block, AnyObject.self))

到目前为止这个工作正常。然而，现在我试图为这个代码构建单元测试。我为SFRestAPI创建了一个模拟类，它是函数sendRESTRequest所在的类。为了测试目的，我试图通过传递从REST服务返回的mockdata来模拟completeBlock：参数。

So far this works fine. However, now I am trying to build unit testing for this code. I have created a mock class for SFRestAPI which is the class where the function "sendRESTRequest" resides. For testing purposes, I am trying to mock out the completeBlock: parameter by passing mock "data" that would be returned from the REST service.

class MockSFRestAPI : SFRestAPI {

    override func sendRESTRequest(request: SFRestRequest!, failBlock: SFRestFailBlock!, completeBlock: AnyObject!) {
        //Convert complete block into a closure and pass in some test data
    }
}

问题是，我无法投射AnyObject！

The issue is, I am unable to cast AnyObject! to a block like I was able to cast the block to AnyObject like above.

我的一些尝试是：

var block = completeBlock as @objc_block (AnyObject! -> Void)
var block2: (AnyObject! -> Void) = unsafeBitCast(completeBlock, (@objc_block (AnyObject! -> Void)))

还有更多的尝试，只有两个似乎相对健全。那么，这是可能在Swift吗？问题似乎是，我不能提供一个闭包类型到unsafeBitCast方法的第二个参数。我想把它变成一个闭包，所以我可以在我的mock方法中调用它，并传递一些假数据。

There have been many more attempts, but these are the only two that seem relatively sane. So, is this possible in Swift? The issue seems to be that I cannot provide a closure "type" to the second parameter of the unsafeBitCast method. I want to turn it into a closure so I can call it in my mock method and pass in some fake data.

推荐答案

最好的方式来处理这种情况是为你的块创建自己的typealias：

The best way to handle this situation is to create your own typealias for your block:

 typealias MyFunBlock = @objc_block (dataResponse :AnyObject!) -> Void;

然后，您可以将其用于unsafebitcast：

Then you can use that to unsafebitcast:

var block: MyFunBlock = unsafeBitCast(completeBlock, MyFunBlock.self) as MyFunBlock;

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