Скачать или смотреть How to Make UIView Animations Work Flawlessly with Keyframes in Swift

Discover how to properly use `UIView.animateKeyframes` in Swift to create smooth animations for your UI elements. Learn how to handle starting times, pauses, and durations.
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This video is based on the question https://stackoverflow.com/q/72973977/ asked by the user 'kelsey-debug' ( https://stackoverflow.com/u/16004664/ ) and on the answer https://stackoverflow.com/a/72981792/ provided by the user 'DonMag' ( https://stackoverflow.com/u/6257435/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Creating Smooth UIView Animations with Keyframes in Swift

Animating your UI elements can significantly improve user experience, and it's crucial to ensure your animations look good and work smoothly. A common problem among developers is when animations skip keyframes or don't behave as expected. In this guide, we'll explore how to correctly use UIView.animateKeyframes to achieve smooth animations like a notification sliding up and down in an iOS application.

The Problem

One of the developers faced an issue while trying to create a sliding notification using the UIView.animateKeyframes function. They wanted the notification to slide up from the bottom of the screen and then slide back down after a few seconds. While their first keyframe worked, adding a second keyframe resulted in the notification skipping the animation and only reaching the endpoint instantly.

The initial attempt looked like this:

[[See Video to Reveal this Text or Code Snippet]]

However, the animation only performed the first keyframe, skipping the second.

Understanding Keyframe Animation

The key to solving this issue lies in understanding how the animateKeyframes function works with relative timings. The relativeStartTime and relativeDuration represent fractions of the total duration of the animation, meaning how much of the total time each keyframe should occupy in proportion to others.

Example of Total Duration

If you wanted an animation where:

The notification slides up for 1 second,

Pauses for 8 seconds,

And then slides down for another 1 second,

Your code should look like this:

[[See Video to Reveal this Text or Code Snippet]]

Breaking Down the Code

Let's break down the revised animation method for clarity:

Define Animation Durations:

Decide how long each part of the animation should take:

[[See Video to Reveal this Text or Code Snippet]]

Calculate Total Duration:

Combine all elements to define the total duration:

[[See Video to Reveal this Text or Code Snippet]]

Convert to Relative Times:

Calculate the percentage for each part of the animation:

[[See Video to Reveal this Text or Code Snippet]]

Animate with Keyframes:

Implement the animation using calculated values for start times:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By understanding UIView.animateKeyframes and how to correctly calculate relative start times and durations, you can create smooth and effective animations in your iOS apps. Whether you're working on sliding notifications or any other form of animation, these principles will guide you in ensuring your UI behaves as expected.

Navigating the challenges of keyframe animations can seem daunting, but with these strategies, you're well-equipped to tackle animation in Swift. Experiment with your animation logic to create engaging and visually appealing interactions in your applications!