相关疑难解决方法(0)

我需要实现使用多页文本创建pdf的功能。

class PDFCreator {

func prepareData() -> Data {
    //1
    let pdfMetaData = [
      kCGPDFContextCreator: "PDF Creator",
      kCGPDFContextAuthor: "Pratik Sodha",
      kCGPDFContextTitle: "My PDF"
    ]

    //2
    let format = UIGraphicsPDFRendererFormat()
    format.documentInfo = pdfMetaData as [String: Any]

    //3
    let pageWidth = 8.5 * 72.0
    let pageHeight = 11 * 72.0
    let pageRect = CGRect(x: 0, y: 0, width: pageWidth, height: pageHeight)

    //4
    let renderer = UIGraphicsPDFRenderer(bounds: pageRect, format: format)

    //5
    let data = renderer.pdfData { (context) in
        //6
        context.beginPage()
        self.addText("Lorem Ipsum is …

在Objective-C中,我能够CGBitmapContextCreate用来创建一个空的上下文.我想在Swift 3中尝试相同,但由于某种原因,它是零.我错过了什么？

let inImage: UIImage = ...
let width = Int(inImage.size.width)
let height = Int(inImage.size.height)

let bitmapBytesPerRow = width * 4
let bitmapByteCount = bitmapBytesPerRow * height

let pixelData = UnsafeMutablePointer<UInt8>.allocate(capacity: bitmapByteCount)

let context = CGContext(data: pixelData,
                                width: width,
                                height: height,
                                bitsPerComponent: 8,
                                bytesPerRow: bitmapBytesPerRow,
                                space: CGColorSpaceCreateDeviceRGB(),
                                bitmapInfo: CGImageAlphaInfo.alphaOnly.rawValue)