如何使用AWS iOS SDK v2检查Amazon S3存储桶上是否存在密钥/文件？

I writing an iOS app that uploads and downloads files from an Amazon S3 bucket. I got said functionality working, but I need to write unit tests for it. Is there any way I can check if a file exists in my bucket so that I can confirm that it has been uploaded??I writing an iOS app that uploads and downloads