I'm working on some code whose purpose is to take an array of NSURLs
and save them as PDFs. I have all the pieces in place, but I'm
getting very strange crashes and I'm just not sure how to proceed.
The issue appears to be related to referencing already released
objects, but since the problem seems to pop up in the middle of an
NSRunLoop, I don't know how to correct or even analyze it.
I've stripped everything down to the bare lines that will result in a
crash and included them below along with some crash information. I
realize it's a lot to sift through, but if anyone could point out
what I'm doing wrong or even just give me a hint on a way to figure
it out on my own, I'd be very grateful.
----Begin Stripped-Down Code----
@implementation J38URL2PDF
NSString *pageTitle;
BOOL loadComplete;
// WebView Delegates
- (void)webView:(WebView *)sender didReceiveTitle:(NSString *)title
forFrame:(WebFrame *)frame
{
if ([sender mainFrame] == frame) {
NSLog(@"didReceiveTitle for mainFrame -- %@",title);
pageTitle = title;
}
}
- (void)webView:(WebView*)webView didFinishLoadForFrame:(WebFrame*)frame
{
if ([webView mainFrame] == frame)
NSLog(@"didFinishLoadForFrame for mainFrame");
loadComplete = YES;
}
- (void)webView:(WebView *)sender didFailProvisionalLoadWithError:
(NSError *)error forFrame:(WebFrame *)frame
{
NSLog(@"didFailProvisionalLoadWithError -- %@ - %@", [error
localizedFailureReason], [error localizedDescription]);
}
- (void)webView:(WebView *)sender didFailLoadWithError:(NSError *)
error forFrame:(WebFrame *)frame
{
NSLog(@"didFailProvisionalLoadWithError -- %@ - %@", [error
localizedFailureReason], [error localizedDescription]);
}
// This is where the action is.
- (id)convertURLs:(id)input
{
WebView* fakeWebView;
fakeWebView = [[WebView alloc] initWithFrame: NSMakeRect
(0,0,612,792)];
[fakeWebView setFrameLoadDelegate:self];
[[fakeWebView preferences] setShouldPrintBackgrounds:YES];
[[fakeWebView preferences] setPlugInsEnabled:NO];
[[fakeWebView preferences] setJavaScriptEnabled:NO];
[[fakeWebView preferences] setJavaEnabled:NO];
NSMutableArray *output = [NSMutableArray arrayWithCapacity:
[input count]];
NSEnumerator *enumerate = [input objectEnumerator];
NSURL *curURL;
while (curURL = [enumerate nextObject]) {
NSLog(@"Trying %@...",[curURL absoluteString]);
[[fakeWebView mainFrame] loadRequest:[NSURLRequest
requestWithURL:curURL]];
pageTitle = nil;
loadComplete = NO;
bool isRunning;
do {
NSDate* next = [NSDate dateWithTimeIntervalSinceNow:1.0];
isRunning = [[NSRunLoop currentRunLoop]
runMode:NSDefaultRunLoopMode beforeDate:next];
} while (!loadComplete && isRunning);
// This is where I start to get the PDF data.
// For whatever reason, including that pdfData assignment is
what causes the program
// to start crashing consistently, though that is *not*
where the crash occurs.
NSView *documentView = [[[fakeWebView mainFrame] frameView]
documentView];
NSData *pdfData = [[NSData alloc] initWithData:[documentView
dataWithPDFInsideRect:[documentView frame]]];
[output addObject:pageTitle];
[pdfData release];
}
[fakeWebView release];
return (output);
}
@end
----End Stripped-Down Code----
----Begin Sample Input Array----
NSArray *input = [[NSArray alloc] initWithObjects:
[NSURL URLWithString: @"
http://telegraph.co.uk/"],
[NSURL URLWithString: @"
http://thesun.co.uk/"],
[NSURL URLWithString: @"
http://guardian.co.uk/"],
[NSURL URLWithString: @"
http://mirror.co.uk/"],
[NSURL URLWithString: @"
http://news.bbc.co.uk/cbbcnews/"],
[NSURL URLWithString: @"
http://news.bbc.co.uk/"],
nil];
----End Sample Input Array----
----Begin Debugger Console Output----
2005-07-23 22:54:22.936 browsish[4036] Trying
http://zvon.org/...
2005-07-23 22:54:23.124 browsish[4036] didReceiveTitle for mainFrame
-- ZVON.org - ZVON
2005-07-23 22:54:23.659 browsish[4036] didFinishLoadForFrame for
mainFrame
2005-07-23 22:54:23.978 browsish[4036] Trying http://
www.tonymarston.net/...
2005-07-23 22:54:23.994 browsish[4036] didReceiveTitle for mainFrame
-- Tony Marston's Home Page
2005-07-23 22:54:24.215 browsish[4036] didFinishLoadForFrame for
mainFrame
2005-07-23 22:54:24.650 browsish[4036] Trying
http://yogajournal.com/...
browsish has exited due to signal 5 (SIGTRAP)..
----End Debugger Console Output----
----Begin system.log Output----
Jul 23 22:54:24 echo /Users/scott/files/code/objective-c/browsish/
build/Debug/browsish.app/Contents/MacOS/browsish: objc: FREED(id):
message release sent to freed object=0x745c400
----End system.log Output----
----Begin Browsish.crash.log Output----
Thread 0 Crashed:
0 libobjc.A.dylib 0x909b6cc0 _objc_trap + 0
1 libobjc.A.dylib 0x909b6c34 _objc_error + 76
2 libobjc.A.dylib 0x909b6bc4 __objc_error + 64
3 com.apple.Foundation 0x92859708 NSPopAutoreleasePool
+ 536
4 com.apple.Foundation 0x928ada88 -[NSURLConnection
(NSURLConnectionInternal) _sendCallbacks] + 660
5 com.apple.Foundation 0x928ad778 _sendCallbacks + 156
6 com.apple.CoreFoundation 0x9074bd2c __CFRunLoopDoSources0
+ 384
7 com.apple.CoreFoundation 0x9074b25c __CFRunLoopRun + 452
8 com.apple.CoreFoundation 0x9074acdc CFRunLoopRunSpecific
+ 268
9 com.apple.Foundation 0x9288bec4 -[NSRunLoop
runMode:beforeDate:] + 172
10 J38URL2PDF.ob 0x000328b4 -[J38URL2PDF
convertURLs:] + 1012 (J38URL2PDF.m:72)
----End Browsish.crash.log Output----
