The official Transloadit iOS-SDK library provides an Objective-C implementation that will probably suffice for many users attempting to use their service, however, it leaves a few things to be desired:
- The library is a bit out of date so there are deprecation warnings
- The library is a bit large and monolithic as it tries to cover all use cases
- The library uses an old syncrhonous API for network connections that make it necessary for the user to use it in an NSOperation or a dispatch_queue
- There is no Swift implementation of the library currently
While none of these are complete show stoppers, they make using the library a little cumbersome. I decided to write a small Swift class the encapsulates the functionality I personally need for my applications and leaves the rest unimplemented. My goals included:
- Build a simple class that handles the network connection and pushing the data to the transloadit server using modern APIs like NSURLSession
- Write the class in Swift using a closure API that makes it simple to be called back after processing
- Add a few convenience functions and extensions to help interrogate the data structure that comes back from Transloadit on a successful upload
- Only allows a single file to be uploaded at a time
- You cannot specify your steps on the app side. They have to be created on the Transloadit website and used directly with an template identifier.
Right. Yeah. No.
Yep. That's it. Copy the file named TransloaditTask.swift from the included project into your own project. Done!
You will, of course, need to add a bridging header because the class uses the common crypto standard library. You can take a look at the bridging header in the sample Xcode project to see how it's done. You're just going to import the Common Crypto library by adding this line to your bridging header:
#import <CommonCrypto/CommonCrypto.h>If you haven't already added a bridging header to your project, you will need to select 'File New | File..." in Xcode and select a header file in the source category.
Make sure you name the file [Project Name]-Bridging-Header.h where '[Project Name]' is the name of the project you're adding it to. Then, in your project settings, specify the path to the bridging header in the "Swift Compler - Code Generation" section--specifically the "Objective-C Bridging Header" field:
The class that I created allows you to perform an upload to Transloadit with the following:
// Grab the image from the image view just to demonstrate uploading a file
if let image = self.imageView.image {
// Create a TransloaditTask object passing it a NSURSession that it will use as well as your API key and secret key
let task = TransloaditTask(session: URLSession.shared, apiKey: transloaditAPIKey, secretKey: transloaditSecretKey)
// These are fields that my template uses. Yours are going to be different if you use them at all.
// See the "Template.json" file in the Xcode project to see how these fields are used on the
// server side.
let fields = ["corp_id" : "AABBCCDDEEFF", "major" : "123456", "minor": "1234567", "device_id" : UIDevice.current.identifierForVendor!.uuidString]
// Turn on the network activity indicator
UIApplication.shared.isNetworkActivityIndicatorVisible = true
// Make sure our image is valid
if let imageData = UIImageJPEGRepresentation(image, 1.0) {
// Call post data on the Transloadit Task object passing it the necessary variables and a completion block
task.postData(imageData, filename: "HotAirBalloon.jpg", fields:fields, templateIdentifier: transloaditTemplate, completion: { (json, response, error) in
// When the request finishes, turn off the network activity indicator
UIApplication.shared.isNetworkActivityIndicatorVisible = false
// Print out the full JSON to the console to see what we got
debugPrint(json as Any)
// Print a list of the steps found in the result JSON
debugPrint(task.resultSteps as Any)
// Alternatively, we can use the overloaded subscript operator on the taksk to retrieve
// the first result from the step called ":original"
if let step1 = task[":original"] {
if let sslURL = step1["ssl_url"] as? String {
// Do something with the SSL URL. Result will be something like:
// https://bucketname.s3.amazonaws.com/AABBCCDDEEFF/123456/1234567/E8B63C90-75C9-4DE7-A0B1-427436262999/HotAirBalloon.jpg
debugPrint(sslURL)
}
}
})
}
}This will upload the file to Transloadit which will make a thumbnail with the size 320x198 and then push both original file and generated thumbnail to a directory I specify using the fields dictionary (see above code) in a bucket in S3. Here is what the template looks like (the key and secret key fields have been obscured. You will need to enter your own to see this work):
Asembly.json
{
"steps": {
"thumb": {
"use": ":original",
"robot": "/image/resize",
"result": true,
"width": 320,
"height": 198,
"resize_strategy": "crop"
},
"store": {
"use": ":original",
"robot": "/s3/store",
"acl": "public-read",
"key": "AWS_API_KEY",
"secret": "AWS_SECRET_KEY",
"path": "${fields.corp_id}/${fields.major}/${fields.minor}/${fields.device_id}/${file.name}",
"bucket": "BUCKET_NAME"
},
"store_thumb": {
"use": "thumb",
"robot": "/s3/store",
"acl": "public-read",
"key": "AWS_API_KEY",
"secret": "AWS_SECRET_KEY",
"path": "${fields.corp_id}/${fields.major}/${fields.minor}/${fields.device_id}/thumbnail_${file.name}",
"bucket": "BUCKET_NAME"
}
}
}The project that I included is a universal iOS application that displays an image in an image view. When you tap an upload button, the app grabs the image in the UIImageView and uploads it to Transloadit using a Template I created in my account (see previous code block for template syntax)
You will need to change these properties to use your own Transloadit credentials and template identifier in the ViewController.swift class:
let transloaditAPIKey = "TRANSLOADIT_API_KEY"
let transloaditSecretKey = "TRANSLOADIT_SECRET_KEY"
let transloaditTemplate = "TRANSLOADIT_TEMPLATE_ID"I don't provide any. Feel free to post questions in the Github issues, but I may or may not answer them. The best/quickest way to add something or make a change is to submit a pull request. I'll take a look and see if it makes sense to merge it in.
Do whatever you want with it. MIT, Apache, Whatever. It's all good.