Use iclems/iOS-htmltopdf to generate multiple pdf from multiple html file - ios

Question

I'm wrapping a for loop for function to enable multiple html to multiple pdf conversion:
for (int i=0; i<= 47; i++) {
NSString *inputHTMLfileName = [NSString stringWithFormat:#"wkhtml_tempfile_%d",j];
NSString *outputPDFfileName = [NSString stringWithFormat:#"~/Documents/%d_delegateDemo%d.pdf",loop,j];
NSURL *htmlFileUrl = [[NSBundle mainBundle]
URLForResource:inputHTMLfileName withExtension:#"html"];
// Check for existing pdf file and remove it
NSError *pdfDeleteError;
if ([[NSFileManager defaultManager] fileExistsAtPath:outputPDFfileName]){
//removing file
if (![[NSFileManager defaultManager] removeItemAtPath:outputPDFfileName error:&pdfDeleteError]){
NSString * errorMessage = [NSString stringWithFormat:#"wk %d Could not remove old pdf files. Error:%#",j, pdfDeleteError];
NSLog(#"%#",errorMessage);
}
}
self.PDFCreator = [NDHTMLtoPDF createPDFWithURL:htmlFileUrl pathForPDF:[outputPDFfileName 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;
}];
}
However, it crashes with
Thread 1: EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
Link to github:
https://github.com/iclems/iOS-htmltopdf
However, if I replace the for loop with a button pressed (trigger this function once per second) the app doesn't crash.

Answer 1

I think your for loop crashing is because you are using block within the for loop
So what happens here is that the another iteration of the calls the block before it completes the previous block call
so here what you can do that you can use dispatch_group feature of ios to call each iteration call on different thread instead of calling sequentially
so to achieve this you can create one method with block parametes and call the block in that method some thing like this,
- (void)blockTask:(NSString*)strPath
{
dispatch_group_enter(serviceGroup);
self.PDFCreator = [NDHTMLtoPDF createPDFWithURL:htmlFileUrl pathForPDF:[outputPDFfileName 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;
dispatch_group_leave(serviceGroup);
} errorBlock:^(NDHTMLtoPDF *htmlToPDF) {
NSString *result = [NSString stringWithFormat:#"HTMLtoPDF did fail (%#)", htmlToPDF];
NSLog(#"%#",result);
self.resultLabel.text = result;
dispatch_group_leave(serviceGroup);
}];
}
Note : This just a psuedo code may contains errors,
For dispatch_group tutorial check here