创建分页的PDF-Mac OS X [英] Create a paginated PDF—Mac OS X

问题描述

我正在制作一个Mac应用程序（在Swift 3使用Xcode 8，Beta 5），用户可以使用它做一个长的笔记，并将其导出为PDF。

要创建此PDF，我使用Cocoa的 dataWithPDF：方法，并使用以下代码：

  do {
 //定义PDF作为注释文本视图的边界
 let rect：NSRect = self.noteTextView.bounds 
 //创建PDF的文件路径
如果let dir = NSSearchPathForDirectoriesInDomains（FileManager.SearchPathDirectory.documentDirectory，FileManager.SearchPathDomainMask.allDomainsMask，true）.first {
 //添加注释标题to path 
 let path = NSURL（fileURLWithPath：dir）.appendingPathComponent（ExportedNote.pdf）
 //创建一个noteTextView的PDF并将其写入创建的文件路径
 try self。 noteTextView.dataWithPDF（inside：rect）.write（to：path！）
} else {
 print（Path format incorrect。）//永远不会发生在我
} 
 
} catch _ {
 print（出了点错误。）//从来没有发生在我身上
} 
  

这完全有效，但有一个问题：PDF只能在一个页面上，这意味着当笔记中有很多文本时，页面变得很长。

解决方案

如何强制PDF转到尽可能多的letter尺寸的页面， / div>

经过几个星期的挫折，我想出了在Swift应用程序中创建一个分页PDF的最终方式。它不像看起来那么复杂（以下是基于 Swift 2 ）：

注意 ：在你阅读更多之前，你应该知道我在Github上做了一个简单的工具，所以你可以在更少的步骤（和在Swift 3，不再需要任何Objective-C）。请检查查看一些非常基础的内容。 。

>

---

学分

• a href =http://stackoverflow.com/questions/39318882/call-an-objective-c-method-from-swift-app>如何在Swift项目中运行Objective-C代码，感谢到Matt。





• http://stackoverflow.com/questions/24002369/how-to-call-objective-c-code-from-swift/24005242#24005242\">如何手动创建桥接头，感谢Logan。


• Swift中的延迟功能，感谢Matt。


• 图片，感谢Logan。

注意：这个答案经过测试可以与Xcode 7， Swift 2和OS X El Captian。如果您在Xcode 8 / Swift 3 / macOS Sierra中使用它有任何问题，请告诉我们。

I am making a Mac app (in Swift 3 using Xcode 8, Beta 5) with which the user can make a long note and export it as a PDF.

To create this PDF, I am using Cocoa's dataWithPDF: method with the following code:

do {
   // define bounds of PDF as the note text view
   let rect: NSRect = self.noteTextView.bounds
   // create the file path for the PDF
   if let dir = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.allDomainsMask, true).first {
        // add the note title to path
        let path = NSURL(fileURLWithPath: dir).appendingPathComponent("ExportedNote.pdf")
        // Create a PDF of the noteTextView and write it to the created filepath
        try self.noteTextView.dataWithPDF(inside: rect).write(to: path!)  
   } else {
        print("Path format incorrect.") // never happens to me
   }

} catch _ {
    print("something went wrong.") // never happens to me
}

This completely works, but there's one problem: the PDF goes only on one page, which means the page gets really long when there's a lot of text in the note. How can I force the PDF to go onto as many letter-size pages as it needs, either while my app is exporting the PDF or right after?

解决方案

After weeks of frustration, I have come up with the definitive way of creating a paginated PDF in a Swift app. And it's not as complicated as it seems (the following is based on Swift 2):

Note: Before you read more, you should know I made an easy tool on Github so you can do this in many fewer steps (and in Swift 3, which no longer needs any Objective-C). Check that out here.

Step 1: Set up your App Sandboxing correctly. Every submitted Mac app requires App Sandboxing correctly, so it's best to just take 30 seconds to set it up right now. If it's not on already, go to your Target's settings and then the Capabilities header. Turn on App Sandboxing, up at the top. You should see many sub-capabilities, enable any one of these your app needs, and make sure to have User Selected File set to Read/Write.

Step 2: Add this function to your code, which will create an invisible webview and add your text into it.

func createPDF(fromHTMLString: String) {
            self.webView.mainFrame.loadHTMLString(htmlString, baseURL: nil)
            self.delay(1) {
            MyCreatePDFFile(self.webView)
    }
}

Step 3: Create the delay() function to allow Xcode to wait a second for the HTML to be loaded into the web view.

 func delay(delay:Double, closure:()->()) {
    dispatch_after(
        dispatch_time(
            DISPATCH_TIME_NOW,
            Int64(delay * Double(NSEC_PER_SEC))
        ),
        dispatch_get_main_queue(), closure)
}

(Note: For the Swift 3 version of this function, go here.)

Step 4: Add the declaration of our WebView above the function you added in step 2.

var webView = WebView()

Step 5: You may notice that we haven't created the MyCreatePDFFile() function yet. Turns out that there is no way to convert this WebView to a PDF with Swift, so we're going to have to turn to Objective-C (groan). Yep, you're going to have to run some Objective-C in your Swift app.

Step 6: Create a .m file by going to File -> New -> File (or by hitting CMD + N) then double-clicking on Objective-C File. Name it CreatePDF.m and leave it as an Empty File.

Step 7: When adding your .m file, you should get a prompt to add a bridging header:

Click Yes.

If you did not see the prompt, or accidentally deleted your bridging header, add a new .h file to your project and name it <#YourProjectName#>-Bridging-Header.h

In some situations, particularly when working with ObjC frameworks, you don't add an Objective-C class explicitly and Xcode can't find the linker. In this case, create your Bridging Header .h file named as mentioned above, then make sure you link its path in your target's project settings like this:

Step 8: Create a .h file by going to File -> New -> File (or by hitting CMD + N) then double-clicking on Header File. Name it CreatePDF.h.

Step 9: In your CreatePDF.h file, add the following code, which imports Cocoa and WebKit and sets up for your PDF creation function:

#ifndef CreatePDF_h
#define CreatePDF_h

#import <Cocoa/Cocoa.h>
#import <WebKit/WebKit.h>

@interface Thing : NSObject

void MyCreatePDFFile(WebView *thewebview);

@end


#endif /* CreatePDF_h */

Step 10: Time to setup the .m file for the PDF creation function. Start by adding this to the empty .m file:

#import "CreatePDF.h"
#import <Cocoa/Cocoa.h>
#import <WebKit/WebKit.h>

@implementation Thing

void MyCreatePDFFile(WebView *thewebview) {

}
@end

Step 11: Now you can add the code to the MyCreatePDFFile(..) function. Here's the function itself (this goes inside the currently-empty void function):

NSDictionary *printOpts = @{
    NSPrintJobDisposition: NSPrintSaveJob // sets the print job to save the PDF instead of print it.
};
NSPrintInfo *printInfo = [[NSPrintInfo alloc] initWithDictionary:printOpts];    
[printInfo setPaperSize:NSMakeSize(595.22, 841.85)]; // sets the paper size to a nice size that works, you can mess around with it
[printInfo setTopMargin:10.0];
[printInfo setLeftMargin:10.0];
[printInfo setRightMargin:10.0];
[printInfo setBottomMargin:10.0];
NSPrintOperation *printOp = [NSPrintOperation printOperationWithView:[[[thewebview mainFrame] frameView] documentView] printInfo:printInfo]; // sets the print operation to printing the WebView as a document with the print info set above
printOp.showsPrintPanel = NO; // skip the print question and go straight to saving pdf
printOp.showsProgressPanel = NO; 
[printOp runOperation];

Step 12: Now add this to your bridging header to allow your Swift file to see that Objective-C function you just made.

#import "CreatePDF.h"

Step 13: There shouldn't be any errors from this code left, but if there are please comment below about them.

Step 14: To call the createPDF function from anywhere your Swift file, do the following:

createPDF("<h1>Title!</h1><p>\(textview.text!)</p>")

The string you see inside createPDF is HTML, and can be edited to anything HTML. If you don't know HTML, you can see some of the very basics right here.

That should be it! You should now be able to create paginated PDFs right from Swift, on Cocoa/Mac apps.

---

Credits

• How to run Objective-C code in a Swift project, thanks to Matt.

• How to write a PDF from a WebView in Obj-C, thanks to some random web forum.

• How to create a bridging header manually, thanks to Logan.
• Delay function in Swift, thanks to Matt.
• Images, thanks to Logan.

Note: This answer was tested to work with Xcode 7, Swift 2, and OS X El Captian. If you have any problems using it with Xcode 8/Swift 3/macOS Sierra, let me know.

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