How can I omit memory when creating a large PDF file
Possible duplicate:
Unable to create PDF document with more than 400 pages on iOS
My application creates PDF files. These PDfs can be large due to the fact that the user can add pages, potentially unlimited, although this is usually ok. 10. I am having problems with iPhone 4 users who are facing a disaster during the PDF distribution phase. Some research work shows the app is running out of memory during the PDF generation phase, I get low memory warnings and then crash. I can reproduce the problem. If I add 50 pages on the iPhone 5, a lot less on the iPhone 4 and not on the simulator that is expected.
Can anyone suggest how I can reduce this acoustic memory maze and maximum crash when generating the PDf file.
Ive researched SO: iPhone lagged behind due to low memory but works great in simulator and Quartz PDF API calling from Memory crash
@interface ICPDFPreviewController ()
@property (nonatomic, strong) Certificate *certificate;
@property (nonatomic, strong) NSData *pdfData;
@property (nonatomic) BOOL viewHasUnloaded;
- (void)generatePdf;
- (void)pdfDone:(NSData *)data;
- (NSData *)createPdfWithPages:(NSArray *)pages;
@end
@implementation ICPDFPreviewController
@synthesize certificate=_certificate;
@synthesize scrollView=_scrollView;
@synthesize webView=_webView;
@synthesize pdfData=_pdfData;
@synthesize viewHasUnloaded=_viewHasUnloaded;
- (void)generatePdf
{
NSMutableArray *pagesArray = [NSMutableArray array];
if ([self.certificate.certificateType.title isEqualToString:@"Minor Works"]) {
[pagesArray addObject:[[ICPDFMinorWorksPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFMinorWorksPage2 alloc] initWithCertificate:self.certificate]];
} else if ([self.certificate.certificateType.title isEqualToString:@"EIC"]) {
[pagesArray addObject:[[ICPDFEICPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage2 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage3 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage4 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage5 alloc] initWithCertificate:self.certificate]];
[self addDistributionBoardsToPagesArray:pagesArray];
ICPDFEICPageFinal *pageFinal = [[ICPDFEICPageFinal alloc] initWithCertificate:self.certificate];
pageFinal.pageNumber.text = [NSString stringWithFormat:@"%d", pagesArray.count+1];
[pagesArray addObject:pageFinal];
} else if ([self.certificate.certificateType.title isEqualToString:@"Domestic EIC"]) {
[pagesArray addObject:[[ICPDFDomesticEICPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFDomesticEICPage2 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFDomesticEICPage3 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFDomesticEICPage4 alloc] initWithCertificate:self.certificate]];
[self addDistributionBoardsToPagesArray:pagesArray];
[pagesArray addObject:[[ICPDFDomesticEICPageFinal alloc] initWithCertificate:self.certificate]];
} else if ([self.certificate.certificateType.title isEqualToString:@"EICR"]) {
[pagesArray addObject:[[ICPDFEICRPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRPage2 alloc] initWithCertificate:self.certificate]];
[self addObservationsToPagesArray:pagesArray];
[self addDistributionBoardsToPagesArray:pagesArray];
[pagesArray addObject:[[ICPDFEICRInspection alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRInspectionPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRInspectionPage2 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRInspectionPage3 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRPageFinal alloc] initWithCertificate:self.certificate]];
}
// Set page count on all pages
int pageNumber = 0;
for (ICCertificateComponent *page in pagesArray) {
page.pageNumber.text = [NSString stringWithFormat:@"%d", ++pageNumber];
page.pageCount.text = [NSString stringWithFormat:@"%d", pagesArray.count];
}
NSData *pdfData = [self createPdfWithPages:pagesArray];
[self performSelectorOnMainThread:@selector(pdfDone:) withObject:pdfData waitUntilDone:YES];
}
- (void)pdfDone:(NSData *)data
{
self.pdfData = data;
[self.webView loadData:self.pdfData MIMEType:@"application/pdf" textEncodingName:@"utf-8" baseURL:nil];
[ICUtils removeProgressView];
}
- (NSData *)createPdfWithPages:(NSArray *)pages
{
// Creates a mutable data object for updating with binary data, like a byte array
NSMutableData *pdfData = [NSMutableData data];
ICCertificateComponent *firstPage = [pages objectAtIndex:0];
UIGraphicsBeginPDFContextToData(pdfData, firstPage.contentView.bounds, nil);
for (int i = 0; i < pages.count; i++) {
ICCertificateComponent *thisPage = [pages objectAtIndex:i];
UIGraphicsBeginPDFPageWithInfo(thisPage.contentView.bounds, nil);
////////////////////////////////////////////////////////////////////
//tried adding this after research on SO, did not stop app crash
// CGContextSetInterpolationQuality((__bridge CGContextRef)(thisPage), kCGInterpolationHigh); CGContextSetRenderingIntent((__bridge CGContextRef)(thisPage), kCGRenderingIntentDefault);
/////////////////////////////////////////////////////////////////////
CGContextRef pdfContext = UIGraphicsGetCurrentContext();
[thisPage.contentView.layer renderInContext:pdfContext];
}
UIGraphicsEndPDFContext();
return pdfData;
}
- (void)addDistributionBoardsToPagesArray:(NSMutableArray *)pagesArray
{
int pageCount = pagesArray.count;
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"createdAt" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
NSArray *boards = [self.certificate.distributionBoards sortedArrayUsingDescriptors:sortDescriptors];
for (DistributionBoard *thisBoard in boards) {
DebugLog(@"Creating a board page");
ICPDFDistributionBoard *boardPage = [[ICPDFDistributionBoard alloc] initWithDistributionBoard:thisBoard];
boardPage.pageNumber.text = [NSString stringWithFormat:@"%d", ++pageCount];
DebugLog(@"Page number is %d", pageCount);
[pagesArray addObject:boardPage];
NSSortDescriptor *circuitDescriptor = [[NSSortDescriptor alloc] initWithKey:@"createdAt" ascending:YES];
NSArray *circuitDescriptors = [[NSArray alloc] initWithObjects:circuitDescriptor, nil];
NSArray *circuits = [thisBoard.circuits sortedArrayUsingDescriptors:circuitDescriptors];
//int circuitCount = circuits.count;
ICPDFCircuitDetails *circuitDetails = boardPage.circuitDetails;
int circuitCount = 0;
for (Circuit *thisCircuit in circuits) {
circuitCount++;
if (circuitCount > 16) {
// Add an extension page
DebugLog(@"Adding an extension sheet");
circuitCount = 1;
ICPDFDistributionBoardExtension *boardExtension = [[ICPDFDistributionBoardExtension alloc] initWithDistributionBoard:thisBoard];
[pagesArray addObject:boardExtension];
boardExtension.pageNumber.text = [NSString stringWithFormat:@"%d", ++pageCount];
circuitDetails = boardExtension.circuitDetails;
}
NSString *key = [NSString stringWithFormat:@"circuitRow%d", circuitCount];
ICCircuitRow *circuitRow = [circuitDetails valueForKey:key];
[circuitRow populateFromCircuit:thisCircuit];
}
}
}
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In general, memory is finite and your generated output is not, so the way to get it to work is to ensure:
- you don't accumulate the entire PDF in memory when you create it.
- You shouldn't unnecessarily store rendering byproducts for each page
In your case, using UIGraphicsBeginPDFContextToData
means you are passing the entire PDF to the ever-expanding NSData. When this data gets too large, you will be killed. Try it instead UIGraphicsBeginPDFContextToFile
. Also in your inner loop for render pages, consider block insertion @autoreleasepool { ... }
to prevent unnecessary creation of objects for a long time. I'm not sure how big your set is pagesArray
, or if this is really what you might think of "swapping" one page at a time when you create it.
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EDIT: I think Ben Zotto's solution is the way to go: use UIGraphicsBeginPDFContextToFile
.
Someone asked this a few months ago. I wrote a memory mapped data receiver that might help:
https://gist.github.com/3748250
Instead of regular memory, a memory-mapped PDF context is used.
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