UIImage 数组到 PDF 转换内存泄漏

Question

我想在 PDF 文档上合并 UIImage，然后它作为数据发送到 API。

但是在这种方法中，存在很大的内存泄漏！它从 20 MB 开始，然后上升到 390 MB，最后内存稳定在 300 MB。

这个方法有什么问题？

fileprivate func mergeImages(_ images: Array<UIImage>)  {
    DispatchQueue.global(qos: .utility).sync {
        let width: CGFloat = 768
        let height: CGFloat = 1024
        let pageSize = CGSize(width: width, height: height);
        let pageFrame = CGRect(x: 0, y: 0, width: width, height: height);
        let pdfData = NSMutableData()

        UIGraphicsBeginPDFContextToData(pdfData, pageFrame, nil)
        let ctx = UIGraphicsGetCurrentContext()

        for i in 0 ..< images.count {
            autoreleasepool {
                let jpegData = UIImageJPEGRepresentation(images[i].resize(toSize: pageSize)!, 0.8)
                let dp = CGDataProvider(data: jpegData! as CFData)
                let cgImage = CGImage(jpegDataProviderSource: dp!, decode: nil, shouldInterpolate: true, intent: .defaultIntent)

                UIGraphicsBeginPDFPage()
                ctx?.translateBy(x: 0, y: height)
                ctx?.scaleBy(x: 1.0, y: -1.0)
                ctx?.draw(cgImage!, in: pageFrame)
            }
            //image.drawInRect(pageFrame)
        }

        UIGraphicsEndPDFContext()
        let d = pdfData as Data
        self.completion?(d)
    }        
}

Answer 1

请尝试对这些对象使用 CGRelease 方法

let jpegData = UIImageJPEGRepresentation(images[i].resize(toSize: pageSize)!, 0.8)
let dp = CGDataProvider(data: jpegData! as CFData)
let cgImage = CGImage(jpegDataProviderSource: dp!, decode: nil, shouldInterpolate: true, intent: .defaultIntent)

因为我怀疑 autorelase 池稍后会释放那些昂贵的对象。