iOS: Reading contents of PDF File - ios

Question

By going to the Quartz 2D programming guide and some of the post on SO I pieced together some code to read the contents of a PDF file. It's failing on the PDF Scanner part, I think. When I go to release the scanner the app crashes with this error:
avi(2282,0x3de7bb88) malloc: *** error for object 0x693f7c0: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
I am opening the PDF file through an email attachment. I know it's at least recognizing the file as I can get the page count. Could someone look at my code below and see where my error is happening? Thanks.
- (void) readPDFFile:(NSURL *)PDFURL {
//make a pdf document and point it to the url of our pdf file
CGPDFDocumentRef pdfDocument;
pdfDocument = CGPDFDocumentCreateWithURL((__bridge CFURLRef)(PDFURL));
//release the url
CFRelease((__bridge CFTypeRef)(PDFURL));
if (pdfDocument) {
//get page count
int pageCount = CGPDFDocumentGetNumberOfPages (pdfDocument);
//
if (pageCount > 0) {
//set up operator table
CGPDFOperatorTableRef pdfOpTable;
pdfOpTable = CGPDFOperatorTableCreate();
//call backs for Op Table
CGPDFOperatorTableSetCallback (pdfOpTable, "MP", &op_MP);
CGPDFOperatorTableSetCallback (pdfOpTable, "DP", &op_DP);
CGPDFOperatorTableSetCallback (pdfOpTable, "BMC", &op_BMC);
CGPDFOperatorTableSetCallback (pdfOpTable, "BDC", &op_BDC);
CGPDFOperatorTableSetCallback (pdfOpTable, "EMC", &op_EMC);
for(int i=0; i<pageCount; i++) {
//set up
CGPDFPageRef thisPage;
CGPDFScannerRef pdfScanner;
CGPDFContentStreamRef thisContentStream;
//get the page
thisPage = CGPDFDocumentGetPage (pdfDocument, i + 1 );
//get the page content stream
thisContentStream = CGPDFContentStreamCreateWithPage (thisPage);
//create a pdf scanner using our previously created table and callbacks
pdfScanner = CGPDFScannerCreate (thisContentStream, pdfOpTable, NULL);
//scan the pdf file
CGPDFScannerScan (pdfScanner); //-->call backs happen here
//release everything
CGPDFPageRelease (thisPage);
/*CGPDFScannerRelease (pdfScanner);
CGPDFContentStreamRelease (thisContentStream);*/
}
}
}
//release the pdf document
CGPDFDocumentRelease(pdfDocument);
}
static void op_MP (CGPDFScannerRef s, void *info) {
const char *name;
if (!CGPDFScannerPopName(s, &name))
return;
NSLog(#"MP /%s\n", name);
}
static void op_DP (CGPDFScannerRef s, void *info) {
const char *name;
if (!CGPDFScannerPopName(s, &name))
return;
NSLog(#"DP /%s\n", name);
}
static void op_BMC (CGPDFScannerRef s, void *info) {
const char *name;
if (!CGPDFScannerPopName(s, &name))
return;
NSLog(#"BMC /%s\n", name);
}
static void op_BDC (CGPDFScannerRef s, void *info) {
const char *name;
if (!CGPDFScannerPopName(s, &name))
return;
NSLog(#"BDC /%s\n", name);
}
static void op_EMC (CGPDFScannerRef s, void *info) {
const char *name;
if (!CGPDFScannerPopName(s, &name))
return;
NSLog(#"EMC /%s\n", name);
}
EDIT: PDFURL comes from this process: User opts to open PDF file attached to email with app. In AppDelegate.m:
- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation
{
/* NSLog(#"Open URL:\t%#\n"
"From source:\t%#\n"
"With annotation:%#",
url, sourceApplication, annotation);*/
NSMutableDictionary* userData = [[NSMutableDictionary alloc] init];
[userData setObject:#"Read PDF" forKey:#"Action"];
[userData setObject:url forKey:#"File Path"];
[[NSNotificationCenter defaultCenter] postNotificationName:#"theMessenger" object:self userInfo: userData];
//NSString *filepath = [url path];
//...
return YES;
}
in viewcontroller.m
- (void) receiveNotification:(NSNotification* ) notification {
...
} else if ([strAction isEqualToString:#"Read PDF"]) {
NSURL* documentURL = [[notification userInfo] objectForKey:#"File Path"];
[self readPDFFile:documentURL];
}
...
EDIT: If I do not release this page app still crashes:
libobjc.A.dylib`objc_release:
0x3be89f20: cmp r0, #0
0x3be89f22: it eq
0x3be89f24: bxeq lr
0x3be89f26: ldr r1, [r0]
0x3be89f28: movs r2, #2
0x3be89f2a: ldr r1, [r1, #16]
0x3be89f2c: bfi r1, r2, #0, #2
0x3be89f30: ldrb r1, [r1]
0x3be89f32: tst.w r1, #2
0x3be89f36: bne 0x3be89f3e ; objc_release + 30
0x3be89f38: movs r1, #0
0x3be89f3a: b.w 0x3be981c0 ; -[NSObject release]
0x3be89f3e: movw r1, #19326
0x3be89f42: movt r1, #507
0x3be89f46: add r1, pc
0x3be89f48: ldr r1, [r1]
0x3be89f4a: b.w 0x3be875a0 ; objc_msgSend
0x3be89f4e: nop

Answer 1

dont release thisPage.. you get it via a GET call not a copy or a create method meaning you don't own it
--
dont release PDURL.. you get it from outside but you don't own it
--
do release the operatorTable .. you CREATE it
AND
dont reuse it for multiple scanners