ios - swift 3 : Transfer Utility enumerateToAssignBlocks method signature

Question

官方 AWS 文档包含以下 objective-c 代码

 AWSS3TransferUtility *transferUtility = [AWSS3TransferUtility defaultS3TransferUtility];
[transferUtility
 enumerateToAssignBlocksForUploadTask:^(AWSS3TransferUtilityUploadTask *uploadTask, __autoreleasing AWSS3TransferUtilityUploadProgressBlock *uploadProgressBlockReference, __autoreleasing AWSS3TransferUtilityUploadCompletionHandlerBlock *completionHandlerReference) {
     NSLog(@"%lu", (unsigned long)uploadTask.taskIdentifier);

     // Use `uploadTask.taskIdentifier` to determine what blocks to assign.

     *uploadProgressBlockReference = // Reassign your progress feedback block.
     *completionHandlerReference = // Reassign your completion handler.
 }
 downloadTask:^(AWSS3TransferUtilityDownloadTask *downloadTask, __autoreleasing AWSS3TransferUtilityDownloadProgressBlock *downloadProgressBlockReference, __autoreleasing AWSS3TransferUtilityDownloadCompletionHandlerBlock *completionHandlerReference) {
     NSLog(@"%lu", (unsigned long)downloadTask.taskIdentifier);

     // Use `downloadTask.taskIdentifier` to determine what blocks to assign.

     *downloadProgressBlockReference =  // Reassign your progress feedback block.
     *completionHandlerReference = // Reassign your completion handler.
 }];

我尝试将其转换为 Swift 3(仅限上传任务)

transferUtility.enumerateToAssignBlocks(forUploadTask:
        {

            let progressPointer = AutoreleasingUnsafeMutablePointer<AWSS3TransferUtilityUploadProgressBlock?>(&uploadProgressBlock)
            let completionPointer = AutoreleasingUnsafeMutablePointer<AWSS3TransferUtilityUploadCompletionHandlerBlock?>(&completionBlock)

            progress = progressPointer
            completion = completionPointer

    }
        , downloadTask: nil)

但是Xcode抛出如下错误

Cannot convert value of type ()->() to expected argument type[...]

有人让它在 Swift 3 中工作吗？可能方法签名已更改

编辑:

我应用了@donkon 的回答:

        transferUtility.enumerateToAssignBlocks(forUploadTask: { (uploadTask:AWSS3TransferUtilityUploadTask, progress:AutoreleasingUnsafeMutablePointer<(@convention(block) (AWSS3TransferUtilityTask, Progress) -> Void)?>?, error: AutoreleasingUnsafeMutablePointer<(@convention(block) (AWSS3TransferUtilityUploadTask, Error?) -> Void)?>?) in

                        let progressPointer = AutoreleasingUnsafeMutablePointer<AWSS3TransferUtilityProgressBlock?>(&self.progressBlock)
                        let completionPointer = AutoreleasingUnsafeMutablePointer<AWSS3TransferUtilityUploadCompletionHandlerBlock?>(&self.completionHandler)
        //

                        progress = progressPointer

                        completion = completionPointer


    }, downloadTask: nil)

现在 Xcode 告诉 progress 和 completion 都是 let 值，不能改变。

Answer 1

您尝试使用的方法的参数是函数。 SDK 中的这些功能是用 Objective-C 编写的。所以你应该使用 @convention(block) 来表明它们是 Objective-C 兼容的 block 引用。

AWSS3TransferUtility.default().enumerateToAssignBlocks(forUploadTask: { (uploadTask:AWSS3TransferUtilityUploadTask, uploadProgressBlockReference:AutoreleasingUnsafeMutablePointer<(@convention(block) (AWSS3TransferUtilityTask, Progress) -> Void)?>?, completionHandlerReference: AutoreleasingUnsafeMutablePointer<(@convention(block) (AWSS3TransferUtilityUploadTask, Error?) -> Void)?>?) in
    print("Hello, world")

    uploadProgressBlockReference?.pointee = {(task:AWSS3TransferUtilityTask, progress:Progress) -> Void in
        print("Fraction completed:  \(progress.fractionCompleted)")
    }
}, downloadTask: nil)