Getting 'unrecognized selector sent to instance' with PDFDocument initWithData?

Question

I'm using jsPDF in a webview to generate a PDF that I'd like to print out on a connected USB label printer. I'm getting a 'unrecognized selector sent to instance' error.

Here is the error from the Xcode console:

-[__NSCFString bytes]: unrecognized selector sent to instance 0x1089cb868

Here is the function for reference:

- (void) printPDFwithPrinter: (NSString *) printerName andData: (NSData *) data{

    NSLog(@"%@", printerName);

    PDFDocument *pdfDocument = [[PDFDocument alloc] initWithData:data];

    NSPrintInfo *printInfo = [NSPrintInfo sharedPrintInfo];
    [printInfo setTopMargin:0.0];
    [printInfo setBottomMargin:0.0];
    [printInfo setLeftMargin:0.0];
    [printInfo setRightMargin:0.0];
    [printInfo setHorizontalPagination:NSFitPagination];
    [printInfo setVerticalPagination:NSFitPagination];
    [printInfo setPrinter:[NSPrinter printerWithName:printerName]];

    PDFPrintScalingMode scale = kPDFPrintPageScaleDownToFit;

    NSPrintOperation *op = [pdfDocument printOperationForPrintInfo: printInfo scalingMode: scale autoRotate: YES];

    [op setShowsPrintPanel:NO];
    [op setShowsProgressPanel:NO];
    [op runOperation];
}

The pdf data is the raw output of the pdf body as a string. (Docs)

I'm brand new to Objective-C, so I'm using AppBurger for my Native/webview bridge (building my app in HTML/JS/CSS).

Here is my Xcode project so far: https://github.com/josiaho/AppBurger-Print-Test

Please [edit] your question to include the complete and exact error message. — rmaddy, Aug 14 '19 at 05:21
Can you also show the code that generates the `NSData` object from which you call your `printPDF:` method? There's no `bytes` function on a `NSString`, b.t.w. — Michael Dautermann, Aug 15 '19 at 03:53
@MichaelDautermann I've added a repository with the entire Xcode project. Thanks! — Josiah, Aug 15 '19 at 06:55

score 1 · Accepted Answer · answered Aug 17 '19 at 10:53

How to debug:

Add a breakpoint on the line PDFDocument *pdfDocument = [[PDFDocument alloc] initWithData:data];
Test the app. When the app hits the breakpoint, inspect data.
data is a NSString and initWithData: expects NSData.

How to fix:

Rename

- (void) printPDFwithPrinter: (NSString *) printerName andData: (NSData *) data

to

- (void) printPDFwithPrinter: (NSString *) printerName andString: (NSString *) string

Convert string to NSData.

NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];

Test the app.

Getting 'unrecognized selector sent to instance' with PDFDocument initWithData?

1 Answers1