In this blog post, we will learn how to add a watermark to a video using AVFoundation in Swift. AVFoundation is a powerful framework for working with audiovisual media on iOS and macOS. It provides a range of functionalities, including the ability to add watermarks to videos.

Creating a Watermark Function
First, let’s create a function that adds a watermark to a video. This function will take a URL of a video and a UIImage of a watermark, and return a mutable composition of the video and the watermark.

Understanding the Code
This function creates a mutable composition and a mutable track, and inserts the video into the track. It creates a layer for the watermark and a layer for the video, and adds them to a parent layer. It creates a mutable video composition and sets its animation tool to a core animation tool that uses the parent layer. It creates a mutable video composition instruction and a mutable video composition layer instruction for the track, and sets them as the instructions of the video composition. Finally, it returns the mutable composition.

Conclusion
In this blog post, we learned how to add a watermark to a video using AVFoundation in Swift. This is a powerful technique that can be used to brand videos, add copyright notices, or provide additional information to viewers. With the power of AVFoundation, you can create professional-quality videos with ease. Happy coding!