如何使用Swift解析PDF頁面中的內容

Question

該文檔對我來說不是很清楚。到目前爲止，我認爲我需要設置一個CGPDFOperatorTable，然後爲每個PDF頁面創建一個CGPDFContentStreamCreateWithPage和CGPDFScannerCreate。

該文件涉及設置回調，但它不清楚如何。如何真正從頁面獲取內容？

這是我的代碼到目前爲止。

let pdfURL = NSBundle.mainBundle().URLForResource("titleofdocument", withExtension: "pdf") 

    // Create pdf document 
    let pdfDoc = CGPDFDocumentCreateWithURL(pdfURL) 

    // Nr of pages in this PF 
    let numberOfPages = CGPDFDocumentGetNumberOfPages(pdfDoc) as Int 

    if numberOfPages <= 0 { 
     // The number of pages is zero 
     return 
    } 

    let myTable = CGPDFOperatorTableCreate() 

    // lets go through every page 
    for pageNr in 1...numberOfPages { 

     let thisPage = CGPDFDocumentGetPage(pdfDoc, pageNr) 
     let myContentStream = CGPDFContentStreamCreateWithPage(thisPage) 
     let myScanner = CGPDFScannerCreate(myContentStream, myTable, nil) 

     CGPDFScannerScan(myScanner) 

     // Search for Content here? 
     // ?? 

     CGPDFScannerRelease(myScanner) 
     CGPDFContentStreamRelease(myContentStream) 

    } 

    // Release Table 
    CGPDFOperatorTableRelease(myTable) 

這是一個類似的問題：PDF Parsing with SWIFT，但還沒有答案。

Answer 1

實際上您已經指定了如何操作，您只需將它放在一起並嘗試操作即可。

首先，你需要設置AA表回調爲你的國家，你自己在你的問題的開始（在Objective C中的所有代碼，而不是斯威夫特）：

CGPDFOperatorTableRef operatorTable = CGPDFOperatorTableCreate(); 
CGPDFOperatorTableSetCallback(operatorTable, "q", &op_q); 
CGPDFOperatorTableSetCallback(operatorTable, "Q", &op_Q); 

此表包含列表您希望獲得的PDF運算符被調用並將回調與它們關聯起來。這些回調只是功能，您在其他位置定義：

static void op_q(CGPDFScannerRef s, void *info) { 
    // Do whatever you have to do in here 
    // info is whatever you passed to CGPDFScannerCreate 
} 

static void op_Q(CGPDFScannerRef s, void *info) { 
    // Do whatever you have to do in here 
    // info is whatever you passed to CGPDFScannerCreate 
} 

，然後創建掃描儀，並得到它去，同時通過它，你剛纔定義的信息。

// Passing "self" is just an example, you can pass whatever you want and it will be provided to your callback whenever it is called by the scanner. 
CGPDFScannerRef contentStreamScanner = CGPDFScannerCreate(contentStream, operatorTable, self); 

CGPDFScannerScan（contentStreamScanner）;

如果您想查看有關如何查找和處理圖像的源代碼的完整示例，請參閱check this website。

Answer 2

這裏是斯威夫特實現回調的例子：

let operatorTableRef = CGPDFOperatorTableCreate() 

    CGPDFOperatorTableSetCallback(operatorTableRef, "BT") { (scanner, info) in 
     print("Begin text object") 
    } 
    CGPDFOperatorTableSetCallback(operatorTableRef, "ET") { (scanner, info) in 
     print("End text object") 
    } 
    CGPDFOperatorTableSetCallback(operatorTableRef, "Tf") { (scanner, info) in 
     print("Select font") 
    } 
    CGPDFOperatorTableSetCallback(operatorTableRef, "Tj") { (scanner, info) in 
     print("Show text") 
    } 
    CGPDFOperatorTableSetCallback(operatorTableRef, "TJ") { (scanner, info) in 
     print("Show text, allowing individual glyph positioning") 
    } 

    let numPages = CGPDFDocumentGetNumberOfPages(pdfDocument) 
    for pageNum in 1...numPages { 
     let page = CGPDFDocumentGetPage(pdfDocument, pageNum) 
     let stream = CGPDFContentStreamCreateWithPage(page) 
     let scanner = CGPDFScannerCreate(stream, operatorTableRef, nil) 
     CGPDFScannerScan(scanner) 
     CGPDFScannerRelease(scanner) 
     CGPDFContentStreamRelease(stream) 
    }