[Interest] iOS Objective-C callback block example connecting back to iOS Qt app?
Edward Sutton
edward.sutton at subsite.com
Sat May 16 19:33:12 CEST 2015
Hi Ben,
I am having Objective-C problems trying to implement a message handler I added to your qisystemutils.mm when it calls NDHTMLtoPDF createPDFWithHTML.
https://github.com/benlau/quickios/blob/master/qisystemutils.mm // <- This is great by the way!
I think I have callback block iissues when createPDFWithHTML is called.
2015-05-16 11:51:10.692 widgets-to-html[86428:769940] -[QIOSApplicationDelegate window]: unrecognized selector sent to instance 0x7fa660547ef0
2015-05-16 11:51:10.693 widgets-to-html[86428:769940] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[QIOSApplicationDelegate window]: unrecognized selector sent to instance 0x7fa660547ef0'
*** First throw call stack:
I suspect blocks and delegates are different ways to do same thing in Objective-C. Can callback blocks be implemented in a static htmlToPdf method?
Do I need to implement a qiviewdelegate equivalent for NDHTMLtoPDF?
File: qisystemutils.mm<https://github.com/benlau/quickios/blob/master/qisystemutils.mm>
———————————
NDHTMLtoPDF *m_htmlToPdfConverter = 0;
static bool htmlToPdf(QVariantMap& data) {
QString pathToHtmlFile = data["pathToHtmlFile"].toString();
QString pathToPdfFile = data["pathToPdfFile"].toString();
NSString* htmlAsBuiltPathDest = pathToHtmlFile.toNSString();
NSURL *baseUrl=[NSURL fileURLWithPath:htmlAsBuiltPathDest];
NSString* pdfOutputFilePath = pathToPdfFile.toNSString();
NSString *html = [NSString stringWithContentsOfFile:htmlAsBuiltPathDest encoding:NSUTF8StringEncoding error:nil];;
if (0 == html) {
return false;
}
// createPDFWithHTML is static method that returns NDHTMLtoPDF
m_htmlToPdfConverter = [NDHTMLtoPDF createPDFWithHTML:(NSString*)html
baseURL:(NSURL*)baseUrl
pathForPDF:pdfOutputFilePath
pageSize:kPaperSizeA4
margins:UIEdgeInsetsMake(10, 5, 10, 5)
successBlock:^(NDHTMLtoPDF *htmlToPDF)
{
NSString *result = [NSString stringWithFormat:@"HTMLtoPDF did succeed (%@ / %@)", htmlToPDF, htmlToPDF.PDFpath];
NSLog(@"%@",result);
}
errorBlock:^(NDHTMLtoPDF *htmlToPDF)
{
NSString *result = [NSString stringWithFormat:@"HTMLtoPDF did fail (%@)", htmlToPDF];
NSLog(@"%@",result);
}];
NSLog(@"***call completed ***");
return true;
}
File: NDHTMLtoPDF.mm
----------------------------------
/// A static method
+ (id)createPDFWithHTML:(NSString*)HTML baseURL:(NSURL*)baseURL pathForPDF:(NSString*)PDFpath pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins successBlock:(NDHTMLtoPDFCompletionBlock)successBlock errorBlock:(NDHTMLtoPDFCompletionBlock)errorBlock
{
NDHTMLtoPDF *creator = [[NDHTMLtoPDF alloc] initWithHTML:HTML baseURL:baseURL delegate:nil pathForPDF:PDFpath pageSize:pageSize margins:pageMargins];
creator.successBlock = successBlock;
creator.errorBlock = errorBlock;
return creator;
}
- (id)initWithHTML:(NSString*)HTML baseURL:(NSURL*)baseURL delegate:(id <NDHTMLtoPDFDelegate>)delegate
pathForPDF:(NSString*)PDFpath pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins
{
if (self = [super init])
{
self.HTML = HTML;
self.URL = baseURL;
self.delegate = delegate;
self.PDFpath = PDFpath;
self.pageMargins = pageMargins;
self.pageSize = pageSize;
[self forceLoadView];
}
return self;
}
//
// NDHTMLtoPDF.h
// Nurves
//
// Created by Clement Wehrung on 31/10/12.
// Copyright (c) 2012-2014 Clement Wehrung. All rights reserved.
//
// Released under the MIT license
#import <UIKit/UIKit.h>
#define kPaperSizeA4 CGSizeMake(595.2,841.8)
#define kPaperSizeLetter CGSizeMake(612,792)
@class NDHTMLtoPDF;
typedef void (^NDHTMLtoPDFCompletionBlock)(NDHTMLtoPDF* htmlToPDF);
@protocol NDHTMLtoPDFDelegate <NSObject>
@optional
- (void)HTMLtoPDFDidSucceed:(NDHTMLtoPDF*)htmlToPDF;
- (void)HTMLtoPDFDidFail:(NDHTMLtoPDF*)htmlToPDF;
@end
@interface NDHTMLtoPDF : UIViewController <UIWebViewDelegate>
@property (nonatomic, copy) NDHTMLtoPDFCompletionBlock successBlock;
@property (nonatomic, copy) NDHTMLtoPDFCompletionBlock errorBlock;
@property (nonatomic, weak) id <NDHTMLtoPDFDelegate> delegate;
@property (nonatomic, strong, readonly) NSString *PDFpath;
@property (nonatomic, strong, readonly) NSData *PDFdata;
+ (id)createPDFWithURL:(NSURL*)URL pathForPDF:(NSString*)PDFpath delegate:(id <NDHTMLtoPDFDelegate>)delegate pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins;
+ (id)createPDFWithHTML:(NSString*)HTML pathForPDF:(NSString*)PDFpath delegate:(id <NDHTMLtoPDFDelegate>)delegate pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins;
+ (id)createPDFWithHTML:(NSString*)HTML baseURL:(NSURL*)baseURL pathForPDF:(NSString*)PDFpath delegate:(id <NDHTMLtoPDFDelegate>)delegate pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins;
+ (id)createPDFWithURL:(NSURL*)URL pathForPDF:(NSString*)PDFpath pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins successBlock:(NDHTMLtoPDFCompletionBlock)successBlock errorBlock:(NDHTMLtoPDFCompletionBlock)errorBlock;
+ (id)createPDFWithHTML:(NSString*)HTML pathForPDF:(NSString*)PDFpath pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins successBlock:(NDHTMLtoPDFCompletionBlock)successBlock errorBlock:(NDHTMLtoPDFCompletionBlock)errorBlock;
+ (id)createPDFWithHTML:(NSString*)HTML baseURL:(NSURL*)baseURL pathForPDF:(NSString*)PDFpath pageSize:(CGSize)pageSize margins:(UIEdgeInsets)pageMargins successBlock:(NDHTMLtoPDFCompletionBlock)successBlock errorBlock:(NDHTMLtoPDFCompletionBlock)errorBlock;
@end
Sorry for my Objective-Confusion. I appreciate the help I have received from Robert and Ben.
Thanks in advance for any suggestions,
-Ed
On May 15, 2015, at 7:29 AM, Robert Iakobashvili <coroberti at gmail.com<mailto:coroberti at gmail.com>> wrote:
Dear Ed,
There is an example attached to this
bug report:
https://bugreports.qt.io/browse/QTBUG-42705
The attached to the bug example code is about
mixing Qt C++ and Obj-C code and sharing text.
May be it could be helpful.
Take care.
Regards,
Robert
On Fri, May 15, 2015 at 3:26 PM, Edward Sutton <edward.sutton at subsite.com<mailto:edward.sutton at subsite.com>> wrote:
Hi Ben,
Thank you very much for sharing your example.
https://github.com/benlau/quickios/blob/master/qisystemutils.mm
Understanding the Objective-C language has been much more difficult than I expected coming from C, C++, and C#.
QMessageBox looks horrible on iOS. I am very glad you have a solution for using UIAlertView in your alertViewCreate method.
UiActionSheet and UIImagePickerController
This has given me much to study and understand.
Thank you again for sharing your iOS code!
-Ed
On May 15, 2015, at 2:33 AM, Ben Lau <xbenlau at gmail.com<mailto:xbenlau at gmail.com>> wrote:
Hi Edward,
You may find example code from my project.
quickios/qisystemutils.mm at master · benlau/quickios<https://github.com/benlau/quickios/blob/master/qisystemutils.mm>
It has implemented an interface to create and communicate to UIAlertView , UIActionSheet , UIImagePickerController etc. It uses a singleton object called SystemMessenger as the bridge between C++ and Objective-C++ code. So that the developed code can be run on non-iOS platform too (for development use)
On 15 May 2015 at 05:53, Edward Sutton <edward.sutton at subsite.com<mailto:edward.sutton at subsite.com>> 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
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