[Interest] iOS Objective-C callback block example connecting back to iOS Qt app?

[Edward Sutton]

Harri,

Thank you.

I think I need to figure out how to:

1 - Pass in a function pointer to the Objective-C code.
2 - The Objective-C callback block calls the function pointer back into the C++ code
3 - C++ code raises a Qt signal
4 - Qt client app receives signal

And figure out any threading issues.

-Ed



On May 15, 2015, at 1:48 AM, Harri Pasanen <harri at mpaja.com<mailto:harri at mpaja.com>> wrote:

Actually it is trivial.

Just rename your Objective-C .m to .mm to make it Objective-C++
Then you can just mix Qt code in the same source.

So your successBlock could read:

    successBlock:^(NDHTMLtoPDF *htmlToPDF) {

        QString *result = QString::fromNSString([NSString stringWithFormat:@"HTMLtoPDF did succeed (%@ / %@)", htmlToPDF, htmlToPDF.PDFpath]);
qDebug() << result;
    }

Only thing you may need to be aware of is threading, the success block
could be called from different thread you Qt code is running.

Hope this helps,

Harri

On 14/05/2015 23:53, Edward Sutton wrote:
Can anyone share an example on how to implement the asynchronous return of a result from an Objective-C callback block to Qt?

For example, see the “successBlock:” below which gets called back asynchronously.

    self.PDFCreator = [NDHTMLtoPDF createPDFWithHTML:(NSString*)html
                                             baseURL:(NSURL*)baseUrl
                                          pathForPDF:[@"~/Documents/hello-world.pdf" stringByExpandingTildeInPath]
                                            pageSize:kPaperSizeA4 margins:UIEdgeInsetsMake(10, 5, 10, 5)
    successBlock:^(NDHTMLtoPDF *htmlToPDF) {

        NSString *result = [NSString stringWithFormat:@"HTMLtoPDF did succeed (%@ / %@)", htmlToPDF, htmlToPDF.PDFpath];
        NSLog(@"%@",result);
        self.resultLabel.text = result;

    }
    errorBlock:^(NDHTMLtoPDF *htmlToPDF) {
        NSString *result = [NSString stringWithFormat:@"HTMLtoPDF did fail (%@)", htmlToPDF];
        NSLog(@"%@",result);
        self.resultLabel.text = result;
    }];


Background:
————————

I need to implement native iOS code to replace the missing QPrinter functionality I used to convert HTML to a PDF report on Android, OS X, Linux, and Windows.

Unfortunately the Qt html-to-pdf functionality is implemented in QPrinter.  This functionality is gone from Qt iOS since iOS has no printer device support,  even though I am not accessing a printer device from iOS.

I found this project which seems to work:

        https://github.com/iclems/iOS-htmltopdf

Objective-C interfacing to C++ is challenging.

Thanks in advance for any tips,

-Ed
This email and any files transmitted with it from The Charles Machine Works, Inc. are confidential and intended solely for the use of the individual or entity to which they are addressed. If you have received this email in error please notify the sender. Our company accepts no liability for the contents of this email, or for the consequences of any actions taken on the basis of the information provided, unless that information is subsequently confirmed in writing. Please note that any views or opinions presented in this email are solely those of the author and do not necessarily represent those of the company. Finally, the recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email.
_______________________________________________
Interest mailing list
Interest at qt-project.org<mailto:Interest at qt-project.org>
http://lists.qt-project.org/mailman/listinfo/interest

_______________________________________________
Interest mailing list
Interest at qt-project.org<mailto:Interest at qt-project.org>
http://lists.qt-project.org/mailman/listinfo/interest

This email and any files transmitted with it from The Charles Machine Works, Inc. are confidential and intended solely for the use of the individual or entity to which they are addressed. If you have received this email in error please notify the sender. Our company accepts no liability for the contents of this email, or for the consequences of any actions taken on the basis of the information provided, unless that information is subsequently confirmed in writing. Please note that any views or opinions presented in this email are solely those of the author and do not necessarily represent those of the company. Finally, the recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/interest/attachments/20150515/d05e35af/attachment.html>