iOS Swift: create a mask from a UILabel - ios

Question

Hi I'm trying to use a label as a mask for a particle emitter layer.
My particles emitter is already set up, but I'm having a problem to get a mask from a label, this is my code that doesn't work so well.
func emitter() {
// define emitter layer as centered w 80% of smallest dimension
let image = emitterImage
let origin = CGPoint(x: view.bounds.midX - view.bounds.width / 2, y: view.bounds.midY - view.bounds.height / 2)
let center = CGPoint(x: view.bounds.midX, y: view.bounds.midY)
let size = CGSize(width: view.bounds.width, height: view.bounds.height)
let rect = CGRect(origin: origin, size: size)
let emitterLayer = CAEmitterLayer()
emitterLayer.emitterShape = CAEmitterLayerEmitterShape.rectangle
emitterLayer.emitterSize = rect.size
emitterLayer.emitterPosition = center
// define cells
let cell = CAEmitterCell()
cell.birthRate = Float(size.width * size.height / 10)
cell.lifetime = 1
cell.velocity = 10
cell.scale = 0.1
cell.scaleSpeed = -0.1
cell.emissionRange = .pi * 2
cell.contents = image.cgImage
emitterLayer.emitterCells = [cell]
// add the layer
view.layer.addSublayer(emitterLayer)
// mask
let font = UIFont(name: "HelveticaNeue", size: 64)!
var unichars = [UniChar]("Text".utf16)
var glyphs = [CGGlyph](repeating: 0, count: unichars.count)
let gotGlyphs = CTFontGetGlyphsForCharacters(font, &unichars, &glyphs, unichars.count)
if gotGlyphs {
let cgpath = CTFontCreatePathForGlyph(font, glyphs[0], nil)!
let path = UIBezierPath(cgPath: cgpath)
let mask = CAShapeLayer()
mask.frame = CGRect(x: 100, y: 100, width: 200, height: 200)
mask.fillColor = UIColor.clear.cgColor
mask.strokeColor = UIColor.white.cgColor
mask.lineWidth = 10.0
mask.path = path.cgPath
emitterLayer.mask = mask
}
}
Problem 1: I got just the first letter ("T") how could I attach all the characters path in one?
if gotGlyphs {
var paths: [UIBezierPath] = []
for glyph in glyphs {
let cgpath = CTFontCreatePathForGlyph(font, glyph, nil)!
let path = UIBezierPath(cgPath: cgpath)
paths.append(path)
}
In this way I got an array of all chars path, but how can I attach them??
Problem 2: The path is rotated by 180 degrees (why???)

Answer 1

Solved Using CATextLayer to create the mask from a label.
let textLayer = CATextLayer()
textLayer.frame = CGRect(x: 0, y: view.bounds.height / 6 * 1, width: yourLabel.frame.width, height: yourLabel.frame.height)
textLayer.rasterizationScale = UIScreen.main.scale
textLayer.contentsScale = UIScreen.main.scale
textLayer.alignmentMode = CATextLayerAlignmentMode.center
textLayer.fontSize = 30
textLayer.font = yourLabel.font
textLayer.isWrapped = true
textLayer.truncationMode = CATextLayerTruncationMode.end
textLayer.string = yourLabel.text
emitterLayer.mask = textLayer