## Upload data

To upload to S3 from a data object, specify the `key` and the `data` object to be uploaded.

<BlockSwitcher>

<Block name="Async/Await">

```swift
let dataString = "My Data"
let data = Data(dataString.utf8)
let uploadTask = Amplify.Storage.uploadData(
    key: "ExampleKey",
    data: data
)
Task {
    for await progress in await uploadTask.progress {
        print("Progress: \(progress)")
    }
}
let value = try await uploadTask.value
print("Completed: \(value)")
```

</Block>

<Block name="Combine">

```swift
let dataString = "My Data"
let data = Data(dataString.utf8)
let uploadTask = Amplify.Storage.uploadData(
    key: "ExampleKey",
    data: data
)
let progressSink = uploadTask
    .inProcessPublisher
    .sink { progress in
        print("Progress: \(progress)")
    }

let resultSink = uploadTask
    .resultPublisher
    .sink {
        if case let .failure(storageError) = $0 {
            print("Failed: \(storageError.errorDescription). \(storageError.recoverySuggestion)")
        }
    }
    receiveValue: { data in
        print("Completed: \(data)")
    }
```

</Block>

</BlockSwitcher>

## Upload file

When you have a file that you want to upload, you can specify the url to the file in the `local` parameter.
If a file with the same `key` already exists in S3, the existing S3 file will be overwritten.
<BlockSwitcher>

<Block name="Async/Await">

```swift
let dataString = "My Data"
let fileNameKey = "myFile.txt"
guard let filename = FileManager.default.urls(
    for: .documentDirectory,
    in: .userDomainMask
).first?.appendingPathComponent(fileNameKey)
else { return }

try dataString.write(
    to: filename,
    atomically: true,
    encoding: .utf8
)

let uploadTask = Amplify.Storage.uploadFile(
    key: fileNameKey,
    local: filename
)

Task {
    for await progress in await uploadTask.progress {
        print("Progress: \(progress)")
    }
}
let data = try await uploadTask.value
print("Completed: \(data)")

```

</Block>

<Block name="Combine">

```swift
let dataString = "My Data"
let fileNameKey = "myFile.txt"
guard let filename = FileManager.default.urls(
    for: .documentDirectory,
    in: .userDomainMask
).first?.appendingPathComponent(fileNameKey)
else { return }

try dataString.write(
    to: filename,
    atomically: true,
    encoding: .utf8
)

let uploadTask = Amplify.Storage.uploadFile(
    key: fileNameKey,
    local: filename
)
progressSink = uploadTask
    .inProcessPublisher
    .sink { progress in
        print("Progress: \(progress)")
    }

resultSink = uploadTask
    .resultPublisher
    .sink {
        if case let .failure(storageError) = $0 {
            print("Failed: \(storageError.errorDescription). \(storageError.recoverySuggestion)")
        }
    }
    receiveValue: { data in
        print("Completed: \(data)")
    }
```

</Block>

</BlockSwitcher>

### Working with Security Scoped Resources (from iCloud)
Security scoped resources refer to files that are retrieved from iCloud  or other cloud storage providers. You're likely to run into these file types when using system components that provide access to files stored in iCloud, e.g. [UIDocumentBrowserViewController](https://developer.apple.com/documentation/uikit/uidocumentbrowserviewcontroller).

To upload security scoped resources, you'll need to:
1. use [startAccessingSecurityScopedResource()](https://developer.apple.com/documentation/foundation/url/1779698-startaccessingsecurityscopedreso) and [stopAccessingSecurityScopedResource()](https://developer.apple.com/documentation/foundation/url/1780153-stopaccessingsecurityscopedresou) to access the data within security scoped files
2. temporarily persist the data from the security scoped files in your app's sandbox 
3. upload files using the temporary URLs
4. delete temporarily persisted files (optional)
```swift
struct ScopedResourceFile {
    let name: String
    let data: Data
}

func getTempUrls(securityScopedUrls: [URL]) -> [URL] {
    // 1. get the content of security scoped resources into ScopedResourceFile struct
    let fileContents = securityScopedUrls.compactMap { url -> ScopedResourceFile? in
        let startAccess = url.startAccessingSecurityScopedResource()
        guard startAccess else {
            print("Issue accessing security scoped resource at :\(url)")
            return nil
        }
        defer { url.stopAccessingSecurityScopedResource() }
        do {
            let data = try Data(contentsOf: url)
            let fileName = url.lastPathComponent
            return ScopedResourceFile(name: fileName, data: data)
        } catch {
            print("Couldn't create Data from contents of file at url: \(url)")
            return nil
        }
    }
    
    // 2. write the file contents to temporary files and return the URLs of the temp files
    let localFileURLs = persistTemporaryFiles(fileContents)

    // 3. Now you have local URLs for the files you'd like to upload.
    return localFileURLs
}
```


## Cancel, Pause, Resume

Calls to `uploadData` or `uploadFile` return a reference to the task that is actually performing the upload.

To cancel the upload (for example, in response to the user pressing a **Cancel** button), you simply call `cancel()` on the upload task.

```swift
func cancelUpload() {
    uploadTask.cancel()
}
```

You can also pause then resume the task.

```swift
uploadTask.pause()
uploadTask.resume()
```


<Callout>

Upload tasks are run using `URLSessionTask` instances internally. You can learn more about them in [Apple's official documentation](https://developer.apple.com/documentation/foundation/urlsessiontask).

</Callout>

## MultiPart upload

Amplify will automatically perform a S3 multipart upload for objects that are larger than 5MB. For more information about S3's multipart upload, see [Uploading and copying objects using multipart upload](https://docs.aws.amazon.com/AmazonS3/latest/userguide/mpuoverview.html)
