edudnyk

import QuartzCore
import UIKit

open class LKLabelLayer : CALayer {
    fileprivate var stringDrawingContext : NSStringDrawingContext!
    fileprivate var stringDrawingOptions : NSStringDrawingOptions!

    @objc open var attributedText : NSAttributedString?
    
    public override init() {

edudnyk

@objc @NSManaged open dynamic var attributedText : NSAttributedString?

open override func action(forKey event: String) -> CAAction? {
    if event == keyPath(\LKLabelLayer.attributedText) {
        /// Create and return our text interpolating `CAAction` instance here
    }
    return super.action(forKey:event)
}

open override class func needsDisplay(forKey key: String) -> Bool {

edudnyk

class LKTextDidChangeAction : CAAnimationGroup {
    /// Here interpolation context gets stored
    @objc var interpolatedAttributeStates : NSMutableDictionary!
    
    var fromAttributedText : NSAttributedString?
    var toAttributedText : NSAttributedString?
    
     required override init() {
        super.init()
    }

edudnyk

let foregroundColorKey = NSAttributedString.Key.foregroundColor.rawValue
let rangeString = NSStringFromRange(NSRange(location:0, length: attributedText.length))
let keyPath = "\(foregroundColorKey).\(rangeString).r"

edudnyk

protocol LKNSDictionaryCoding {
    static func lk_dictEncode(object: AnyObject?)->NSMutableDictionary
    static func lk_dictDecode(dictionaryRepresentation dictionary: NSDictionary?)->Self
}

edudnyk

extension UIColor : LKNSDictionaryCoding {
    
    static func lk_dictEncode(object: AnyObject?)->NSMutableDictionary {
        let color = object as? UIColor
        var red: CGFloat = 0, 
          green: CGFloat = 0, 
           blue: CGFloat = 0, 
          alpha: CGFloat = 0
        if color?.getRed(&red, 
                        green: &green, 

edudnyk

var animations = [CABasicAnimation]()
let rootAttributesKey = keyPath(\LKLabelLayer.currentTextDidChangeAnimation?
                                                            .interpolatedAttributeStates)
type(of: self).attributedStringKeys.forEach { (attributeRawValue) in

    var shorterTextValue : AnyObject? = nil
    let attributedStringKey = NSAttributedString.Key(rawValue: attributeRawValue)
    let swapped = self.toAttributedText?.length ?? 0 > self.fromAttributedText?.length ?? 0
    let longerText = swapped ? self.toAttributedText : self.fromAttributedText
    let shorterText = swapped ? self.fromAttributedText : self.toAttributedText

edudnyk

private static func animationsForAttributeDiff(forRootKey rootKey: String,
                                       attributedStringKey: NSAttributedString.Key,
                                       fromValue: Any?,
                                       toValue: Any?,
                                       in diffRange: NSRange,
                                       attributeStates : NSMutableDictionary,
                                       duration: TimeInterval)->[CABasicAnimation] {
    var animations = [CABasicAnimation]()
    let appendAnimation : (_ keyPath: String, _ from: Any?, _ to: Any?)->() = 
          { (keyPath, from, to) in

edudnyk

var interpolatedFromAttributedText : NSAttributedString? {
    get {
        return fill(withInterpolatedAttributes: fromAttributedText)
    }
}
var interpolatedToAttributedText : NSAttributedString? {
    get {
        if toAttributedText != nil {
            return fill(withInterpolatedAttributes: toAttributedText!)
        }

edudnyk

private static func animationsForAlphaSwap(forKeyPath keyPath: String, 
                                                    fromValue: Any?, 
                                                      toValue: Any?)->[CABasicAnimation] {
    let duration = CATransaction.animationDuration()
    guard duration > 0 else { return [CABasicAnimation]() }
    let alphaSwapDuration = min(LabelLayerFromToAlphaSwapAnimationDuration, 0.5 * duration)
    let alphaPersistDuration = (duration - alphaSwapDuration) / 2.0
    let persistFromAlphaAnimation = CABasicAnimation(forKeyPath: keyPath, 
                                                      fromValue: fromValue, 
                                                        toValue: fromValue,