LineByLineTextAnimator 🎬✨

WWDC‑style per‑line text reveal & hide animation for UILabel 🚀

📹 Preview

IMG_0675.MP4

🎯 Features

• 🔠 Line‑by‑line staggered animation (cascade)
• ↕️ Opacity 0 → 1 and Y‑offset 8pt → 0
• 📐 Scale 0.96 → 1.0 (anchor at bottom)
• 🌫️ Blur 8 → 0 (iOS 17+ GPU via CIFilter; fallback on iOS 16 to UIVisualEffectView)
• ▶️ Animate In (animateIn) and ⏹️ Animate Out (animateOut)
• 🪄 Triggers only when the label’s superview exists
• ⚡️ Caching of TextKit line layout for performance

📋 Requirements

• iOS 16.4+
• Swift 5.7+
• UIKit

ℹ️ Important: The original UILabel being animated must have:

• lineBreakMode = .byWordWrapping
• Initially isHidden = true

🚀 Installation

1. Copy LineByLineTextAnimator.swift into your project.

2. Ensure you import:

   import UIKit
   import CoreText
   import CoreImage

🔧 Usage

Reveal (Animate In) ▶️

// Ensure label.frame is final and label.layoutIfNeeded() has been called
label.isHidden = true  // initial state
LineByLineTextAnimator.animateIn(
    label: label,           // your multiline UILabel
    totalDuration: 0.56,    // optional, default 0.56s
    cascadeFraction: 0.45   // optional, default 0.45
)

Hide (Animate Out) ⏹️

// Hide immediately and play reverse animation
label.isHidden = true
LineByLineTextAnimator.animateOut(
    label: label,
    totalDuration: 0.56,
    cascadeFraction: 0.45
)

📦 Example

In your view controller:

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    // Reveal once
    label.isHidden = true
    LineByLineTextAnimator.animateIn(label: label)
}

@IBAction func didTapHide(_ sender: UIButton) {
    // Hide on demand
    label.isHidden = true
    LineByLineTextAnimator.animateOut(label: label)
}

🔄 Customization

• Timing: adjust totalDuration & cascadeFraction.
• Spring physics: tweak UISpringTimingParameters(mass:stiffness:damping:initialVelocity:) in the code.
• Blur radius: modify values in the CIFilter or fallback animation.

⚡️ Performance Tips

• Call label.layoutIfNeeded() before animation.
• Reuse UILabels to benefit from line‑layout caching.

📜 License

MIT — free to use and modify.