Checking metadata of Amazon S3 file using iOS AWS SDK in Swift - ios

Question

I am using the AWS iOS SDK v2, and Swift 1.2.
I am storing my app's app.json file on S3 and want to check it at launch to see if it's been updated since the last run. According to research, simply doing a HEAD request on the object should return the "Last-Modified" attribute which can then be compared to the previous.
The problem is that doing a HEAD request on an Object doesn't really seem to be well documented. I've got the following:
var metaDataRequest = AWSS3HeadObjectRequest()
metaDataRequest.bucket = S3BucketName
metaDataRequest.key = S3AppJSONKey
This seems like a decent start, however I cannot find a way to execute the request. The AWSS3TransferManager has a download() method, but the method requires an AWSS3TransferManagerDownloadRequest type, which an AWSS3HeadObjectRequest cannot be cast as.
Not sure where to go from here, short of just doing the request outside of the SDK. I did, however, want to leverage as much of the SDK as possible, so if this is possible I would love to know how.

Answer 1

You need to use AWSS3 (instead of AWSS3TransferManager) to call - headObject:.

Answer 2

You need to call headobject method of AWSS3
var request = AWSS3HeadObjectRequest()
request.bucket = "flkasdhflhad"
request.key = "hfsdahfjkhadjkshf"
request.ifModifiedSince = NSDate()
var s3 = AWSS3.defaultS3()
s3.headObject(request) { ( output1 : AWSS3HeadObjectOutput?, error : NSError?) -> Void in
print( output1?.description())
}
if your object is modified from specified date then it will return u the object otherwise it will return u the status code 304.

Answer 3

You can use following Swift 2.2 method to check if file exist or not
func checkIfFileExist() {
let s3 = AWSS3.defaultS3()
let headObjectsRequest = AWSS3HeadObjectRequest()
headObjectsRequest.bucket = "YourBucketName" //Don't add "/" at end of your bucket Name
headObjectsRequest.key = "YourFileNameYouWantToCheckFor" //Don't add "/" in start of file name
s3.headObject(headObjectsRequest).continueWithBlock { (task) -> AnyObject! in
if let error = task.error {
print("Error to find file: \(error)")
} else {
print("fileExist")
}
}
}
Note: Example to set bucket and key
suppose you have bucket named "ABC" and than folder named "XYZ" and than inside "XYZ" you have file "abc123"
than write
headObjectsRequest.bucket = "ABC/XYZ"
and
headObjectsRequest.key = "abc123"
and if you want to check for the entire folder
than use
headObjectsRequest.bucket = "ABC/XYZ"
and
headObjectsRequest.key = ""
Thanks Mohsin