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Custom CDN

By default, files are uploaded to Stream's CDN, but you can also use your own CDN. Currently, there are two options to provide your custom file uploading logic.

  • Providing a CDNClient implementation. This is the simplest one and it is useful if you are only interested in changing the CDN URL and do not want to update the attachment payload.

  • Providing an AttachmentUploader implementation. This one can be used for more fine-grain control, since you can change not only the URL but the attachment payload as well.

note

You should only pick 1 of the 2 options provided. Since using an AttachmentUploader will override the custom CDNClient implementation.

Custom CDNClient implementation#

In case you simply want to change the URL, here is an example of a custom CDNClient implementation.

// Example of your Upload API
protocol UploadFileAPI {
func uploadFile(data: Data, progress: ((Double) -> Void)?, completion: (@escaping (FileDetails) -> Void))
}
protocol FileDetails {
var url: URL { get }
}

final class CustomCDNClient: CDNClient {
/// Example, max 100 MB. Required by CDNClient protocol.
static var maxAttachmentSize: Int64 { 100 * 1024 * 1024 }

let uploadFileApi: UploadFileAPI

init(uploadFileApi: UploadFileAPI) {
self.uploadFileApi = uploadFileApi
}

func uploadAttachment(
_ attachment: AnyChatMessageAttachment,
progress: ((Double) -> Void)?,
completion: @escaping (Result<URL, Error>
) -> Void) {
// The local file url is present in attachment.uploadingState.
guard let uploadingState = attachment.uploadingState,
let fileData = try? Data(contentsOf: uploadingState.localFileURL) else {
return completion(.failure(ClientError("Failed to upload attachment with id: \(attachment.id)")))
}

uploadFileApi.uploadFile(data: fileData, progress: progress) { file in
completion(.success(file.url))
}
}

}

Then, you can set your custom implementation in the ChatClientConfig:

var config = ChatClientConfig(apiKeyString: apiKeyString)   
config.customCDNClient = CustomCDNClient(uploadFileApi: YourUploadFileApi())
note

In case your API does not support progress updates, you can simple ignore the argument.

Custom AttachmentUploader implementation#

If you require changing more details of the attachment, in case your upload file API supports more features, you can provide a custom AttachmentUploader.

// Example of your Upload API
protocol UploadFileAPI {
func uploadFile(data: Data, progress: ((Double) -> Void)?, completion: (@escaping (FileDetails) -> Void))
}
protocol FileDetails {
var name: String { get set }
var url: URL { get }
var thumbnailURL: URL { get set }
var codec: String { get set }
}

final class CustomUploader: AttachmentUploader {

private let attachmentUpdater = AnyAttachmentUpdater()

let uploadFileApi: UploadFileAPI

init(uploadFileApi: UploadFileAPI) {
self.uploadFileApi = uploadFileApi
}

func upload(
_ attachment: AnyChatMessageAttachment,
progress: ((Double) -> Void)?,
completion: @escaping (Result<UploadedAttachment, Error>) -> Void
) {
// The local file url is present in attachment.uploadingState.
guard let uploadingState = attachment.uploadingState,
let fileData = try? Data(contentsOf: uploadingState.localFileURL) else {
return completion(.failure(ClientError("Failed to upload attachment with id: \(attachment.id)")))
}

uploadFileApi.uploadFile(data: fileData, progress: progress) { [weak self] file in
var uploadedAttachment = UploadedAttachment(
attachment: attachment,
remoteURL: file.url
)

// Update the image payload, in case the attachment is an image.
self?.attachmentUpdater.update(
&uploadedAttachment.attachment,
forPayload: ImageAttachmentPayload.self
) { payload in
payload.title = file.name
payload.extraData = [
"thumbnailUrl": .string(file.thumbnailURL)
]
}

// Update the audio payload, in case the attachment is a audio.
self?.attachmentUpdater.update(
&uploadedAttachment.attachment,
forPayload: AudioAttachmentPayload.self
) { payload in
payload.title = file.name
payload.extraData = [
"thumbnailUrl": .string(file.thumbnailURL),
"codec": .string(file.codec)
]
}

completion(.success(uploadedAttachment))
}
}
}

The AnyAttachmentUpdater is a helper component provided by Stream, to make it easier to update the underlying payload of a type-erased attachment. You should pass a reference of the attachment with & and say which payload to update depending on what type is the attachment.

Finally, you should set your custom implementation in the ChatClientConfig:

var config = ChatClientConfig(apiKeyString: apiKeyString)   
config.customAttachmentUploader = CustomUploader(uploadFileApi: YourUploadFileApi())

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