String to [[Bool]]

text2bitmap.swift

import Foundation
import Cocoa

func text2bitmap(text: String, font: NSFont) -> [[Bool]]? {
    let attributes = [NSAttributedStringKey.font:font]
    let size = text.size(withAttributes: attributes)
    let width = Int(size.width)
    let height = Int(size.height)
    
    let bytesPerRow = width
    let dataSize = bytesPerRow * height
    var pixelData = [UInt8](repeating: 0, count: dataSize)
    let colorSpace = CGColorSpaceCreateDeviceGray()
    guard let context = CGContext(data: &pixelData,
                                  width: width,
                                  height: height,
                                  bitsPerComponent: 8,
                                  bytesPerRow: bytesPerRow,
                                  space: colorSpace,
                                  bitmapInfo: CGImageAlphaInfo.alphaOnly.rawValue)
        else {
            return nil
    }
    context.setShouldAntialias(false)
    
    NSGraphicsContext.saveGraphicsState()
    NSGraphicsContext.current = NSGraphicsContext(cgContext: context, flipped: false)
    text.draw(at: NSPoint.zero, withAttributes: attributes)
    NSGraphicsContext.restoreGraphicsState()
    
    var isTop = true
    var bitmap = [[Bool]]()
    for i in 0..<height {
        var line = [Bool]()
        for j in 0..<width {
            let pix = pixelData[i * bytesPerRow + j]
            line.append(pix > 128)
        }
        if isTop {
            if line.contains(true) {
                isTop = false
                bitmap.append(line)
            }
        } else {
            bitmap.append(line)
        }
    }
    
    while let last = bitmap.last, last.contains(true) == false {
        bitmap.removeLast()
    }
    
    return bitmap
}


let text = "1"
if
    let font = NSFont(name: "Helvetica", size: 8),
    let bitmap = text2bitmap(text: text, font: font)
{
    for line in bitmap {
        var txt = ""
        for pix in line {
            txt += pix ? "■" : "□"
        }
        print(txt)
    }
}