Print to printer via Bluetooth(non Airprint) in iOS? - ios

Question

I need to print an image from my iOS app to bluetooth thermal printer which is not AirPrint enabled. As we can not use UIKit print for non AirPrint printer, I chose to use 3rd party SDK.
Used this SDK and tried to print image where i can print small sized images, but when it comes to large one, it got crash on appending bytes saying index out of range, this is the function
`private func eachLinePixToCmd(src: [UInt8], nWidth: Int, nHeight: Int, nMode: Int) -> [UInt8] {
var data = [UInt8]
let p0 = [0, 0x80]
let p1 = [0, 0x40]
let p2 = [0, 0x20]
let p3 = [0, 0x10]
let p4 = [0, 0x08]
let p5 = [0, 0x04]
let p6 = [0, 0x02]
let nBytesPerLine: Int = (nWidth + 7) / 8
var k: Int = 0
for _ in 0..<nHeight {
data.append(ESC_POSCommand.beginPrintImage(xl: UInt8(nBytesPerLine % 0xff), xH: UInt8(nBytesPerLine / 0xff), yl: UInt8(1), yH: UInt8(0)).rawValue)
var bytes = [UInt8]()
for _ in 0..<nBytesPerLine {
bytes.append(UInt8(p0[Int(src[k])] + p1[Int(src[k + 1])] + p2[Int(src[k + 2])] + p3[Int(src[k + 3])] + p4[Int(src[k + 4])] + p5[Int(src[k + 5])] + p6[Int(src[k + 6])] + Int(src[k + 7])))
k = k + 8
}
data.append(bytes)
}
let rdata: [UInt8] = data.flatMap { $0 }
return rdata
}
}`
Please let me know if any other SDK available or where to make changes on appending bytes?
Hope for the reply!!

Answer 1

I faced the same issue with the print images, this is due to thermal printer limitations. Here I have compressed the image before sending it to print image.
func resizeWithWidth(width: CGFloat) - > UIImage ? {
let imageView = UIImageView(frame: CGRect(origin: .zero, size: CGSize(width: width, height: CGFloat(ceil(width / size.width * size.height)))))
imageView.contentMode = .scaleAspectFit
imageView.image = self
UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, false, scale)
guard
let context = UIGraphicsGetCurrentContext()
else {
return nil
}
imageView.layer.render( in: context)
guard
let result = UIGraphicsGetImageFromCurrentImageContext()
else {
return nil
}
UIGraphicsEndImageContext()
return result
}
//Set the width to 256 for example
let myImage = image.resizeWithWidth(width: 256) !
let compressData = myImage.jpegData(compressionQuality: 0.6)
//max value is 1.0 and minimum is 0.0
let compressedImage = UIImage(data: compressData!)
var ticImage = Ticket(.image(image, attributes: .alignment(.center)))
if bluetoothPrinterManager.canPrint {
bluetoothPrinterManager.print(ticImage)
}