How to parse SVG path component to UIBezierPath using SVGKit in iOS? - ios

Question

I am animating a SVG image in iOS using Swift. I have been able to render the SVG easily using SVGKit (https://github.com/SVGKit/SVGKit) but to animate it I need to convert the SVG path element to UIBezierPath. I can do so using other libraries but it'd be nice if I could do all of it using SVGKit alone. I haven't find any straight forward way to get the path element as well.

Answer 1

I had the same issues with Swift and using SVGKit. Even after following this simple tutorial and converting it to swift, I could render the SVG but not animate the line drawing. What worked for me was switching to PocketSVG
They have a function to iterate over each Layer and this is how I used it to animate a SVG file:
let url = NSBundle.mainBundle().URLForResource("tiger", withExtension: "svg")!
let paths = SVGBezierPath.pathsFromSVGAtURL(url)
for path in paths {
// Create a layer for each path
let layer = CAShapeLayer()
layer.path = path.CGPath
// Default Settings
var strokeWidth = CGFloat(4.0)
var strokeColor = UIColor.blackColor().CGColor
var fillColor = UIColor.whiteColor().CGColor
// Inspect the SVG Path Attributes
print("path.svgAttributes = \(path.svgAttributes)")
if let strokeValue = path.svgAttributes["stroke-width"] {
if let strokeN = NSNumberFormatter().numberFromString(strokeValue as! String) {
strokeWidth = CGFloat(strokeN)
}
}
if let strokeValue = path.svgAttributes["stroke"] {
strokeColor = strokeValue as! CGColor
}
if let fillColorVal = path.svgAttributes["fill"] {
fillColor = fillColorVal as! CGColor
}
// Set its display properties
layer.lineWidth = strokeWidth
layer.strokeColor = strokeColor
layer.fillColor = fillColor
// Add it to the layer hierarchy
self.view.layer.addSublayer(layer)
// Simple Animation
let animation = CABasicAnimation(keyPath:"strokeEnd")
animation.duration = 4.0
animation.fromValue = 0.0
animation.toValue = 1.0
animation.fillMode = kCAFillModeForwards
animation.removedOnCompletion = false
layer.addAnimation(animation, forKey: "strokeEndAnimation")

Answer 2

The path is available by calling .path on Apple's classes. I suggest you read the Apple CoreAnimation documentation, especially CAShapeLayer (which is used heavily by SVGKit).
Apple also provides code for converting to UIBezierPath - again, search the Apple docs for details on how to do this. e.g.:
(UIBezierPath *)bezierPathWithCGPath:(CGPathRef)CGPath;