Animating Charts and Graphs in Mobile Apps

We've seen it countless times: a client brings a mockup with a chart where bars shoot up one after another and a line flows like a painter's brushstroke. At first glance, it's a simple animation. But when it comes to code, the off-the-shelf library doesn't support that stagger effect, and a custom Canvas implementation demands deep understanding of Core Animation or the Android Canvas API. We take on such tasks and implement animations of any complexity in 1–3 days — be it a bar chart, line chart, or pie chart. In this article, we'll walk through typical problems and how to solve them.

Before choosing a library or writing from scratch, it's important to understand what animations are needed: simple appearance or sequential stagger, touch-event handling and tooltips, working with large datasets (500+ points) without FPS drops. We use profiling (Instruments, Android Profiler) at every stage to guarantee 60fps.

How to Choose Between a Library and Custom Canvas?

The decision between a ready-made library and a custom implementation is key. Libraries like MPAndroidChart or Swift Charts give you 80% of what you need in 20% of the time, but animation customization is limited. For example, MPAndroidChart supports animateX() and animateY(), but customizing easing per bar or creating a stagger animation (bars appearing one by one) is impossible without a custom Renderer. Custom Canvas is justified when you need a non-standard chart type, stagger effect, animation of individual points, or interactive tooltips.

Why Stagger Animation Matters for Data Perception

Stagger animation (sequential appearance of elements) draws attention to each bar or point, making the data more readable. Custom Canvas implementation gives you 3 times more control over animation compared to ready-made libraries, which is critical for complex dashboards. We implemented it in Flutter using AnimationController + Interval:

// Each bar animates with an 80ms delay for (int i = 0; i < bars.length; i++) { final start = (i * 0.08).clamp(0.0, 1.0); final end = (start + 0.4).clamp(0.0, 1.0); animations[i] = Tween(begin: 0.0, end: bars[i].value).animate( CurvedAnimation( parent: controller, curve: Interval(start, end, curve: Curves.easeOutCubic), ), ); } 

On iOS, a similar effect is achieved via CAKeyframeAnimation with keyTimes — each CAShapeLayer (one bar) gets a shifted beginTime:

bars.enumerated().forEach { index, layer in let anim = CABasicAnimation(keyPath: "bounds.size.height") anim.beginTime = CACurrentMediaTime() + Double(index) * 0.08 anim.duration = 0.4 anim.timingFunction = CAMediaTimingFunction(name: .easeOut) layer.add(anim, forKey: nil) } 

A line chart is animated via CAShapeLayer with strokeEnd: 0 → 1. To add marker points that appear as the "brush" passes by, synchronize the appearance of CALayer with the strokeEnd progress. We implement this through CAAnimationDelegate.animationDidStop for each segment or via a displayLink tracking presentation().strokeEnd.

Interactive Tooltip: How to Maintain FPS

A tooltip that follows the finger across the graph is a separate challenge. On iOS: UIGestureRecognizer → map coordinate to data value → UIView.animate for the tooltip. It's crucial to call setNeedsDisplay() only on the part of CALayer that draws the highlight line — redrawing the entire canvas kills FPS during fast finger movement. We guarantee 60fps even with intensive interaction thanks to incremental rendering.

What's Included in Our Work

• Source code of the animated component in Swift/Kotlin/Dart/TypeScript
• Documentation for customization (colors, fonts, animation parameters)
• Integration into your existing project and test environment setup
• Performance optimization (downsampling for sets >500 points, LOD)
• 60fps guarantee on mid-range devices

We have been developing mobile apps for over 5 years and have completed over 15 projects with animated graphics (fintech, analytics dashboards). Our tech stack includes: SwiftUI + Combine, Jetpack Compose + Coroutines, Flutter 3.x. Apple's animation recommendations: use CAMediaTiming for synchronization.

How to Implement Stagger Animation in 4 Steps

1. Initialize an AnimationController (or CADisplayLink).
2. Create an array of delays: delay = index * intervalTime.
3. For each element, apply a Tween animation with CurvedAnimation and Interval.
4. Start the master controller — elements will animate sequentially.

Contact us to discuss your graph — we'll evaluate your project for free. Order turnkey chart animation development.