Spitfire

Spitfire is a simple utility for taking an array of images and creating a video from them.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

The following code can be found in the example project, but demonstrates how to call it and handle the various callbacks it supports.

To initialize an instance of Spitfire, you must provide a delegate. A common way of doing this within a UIViewController would be to use a lazy property like this:

lazy var spitfire: Spitfire = {
    return Spitfire(delegate: self)
}()

And a function for creating the video, using [UIImage] called images, and with a framerate of 30 fps:

spitfire.makeVideo(with: images, fps: 30)

Spitfire will return feedback via a set of delegate functions. This includes the following:

• Progress status --- Will contain a Progress object that you can use for updating your UI on the status of writing out the video
• Completion, including URL --- Will contain the URL on the file system for when the video has been written
• Failure, including error --- Will contain a SpitfireError highlighting what part failed

The Spitfire delegate protocol:

public protocol SpitfireDelegate: class {
    func videoProgress(progress: Progress)
    func videoCompleted(url: URL)
    func videoFailed(error: SpitfireError)
}

Performance Considerations

Be aware that the image array to feed the writer can start to get immense, easily exceeding 1GB of RAM. Be mindful of this when creating videos, otherwise you run the risk of crashing due to memory usage. A general rule of thumb would be to keep your video clips under one minute, but this will vary based on the size of images and device.

Requirements

• iOS 11.0+
• Xcode 10.2+
• Swift 5.0+

Installation

Spitfire is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "Spitfire"

Usage

import Spitfire

Ensure that you declare the Spitfire property at the class level so that it does not go out of scope during execution:

class MyClass {
    lazy var spitfire: Spitfire = {
        return Spitfire(delegate: self)
    }()
    ...
}

Call the makeVideo function, and accept the default value of 30 for framerate:

spitfire.makeVideo(with: images)

Call the makeVideo function and specify a frame rate between 1 and 60:

spitfire.makeVideo(with: images, fps: 60)

Calling the makeVideo function with a value outside of 1-60 will result in an invalidFramerate error.

Errors

Spitfire provides a relatively rich set of errors via an enum that should address all potential failures within the app. These are:

public enum SpitfireError: Swift.Error {
    case imageArrayEmpty
    case invalidFramerate(String)
    case imageDimensionsMatchFailure
    case imageDimensionsMultiplierFailure(String)
    case videoWriterFailure
    case pixelBufferPointeeFailure
    case invalidStatusCode(Int)
    case pixelBufferApendFailure
}

Credits

This work is based off of work originally performed by acj which can be found here.

License

Spitfire is available under the MIT license. See the LICENSE file for more info.