NSStream Released while reading in, "EXC_BAD_ACCESS" iPhone SDK - iphone

Question

I have a view controller that is an NSStreamDelegate, I have a problem when the view is popped from the navigation controller while something is being streamed I get a "EXC_BAD_ACCESS" error. I have tried closing the stream, but it doesn't seem to stop it if there is a stream in progress. What is the proper way to handle this, can you delay the view from popping if something is being streamed?
#import "CameraViewer.h"
#implementation CameraViewer
#synthesize camService;
#synthesize currentDownload;
// The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil theService:(NSNetService *)cameraService {
if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
// Custom initialization
[self setCamService:cameraService];
}
return self;
}
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
[self downloadAgain];
}
- (void)viewWillDisappear:(BOOL)animated{
NSLog(#"view is going away");
NSInputStream *istream;
[camService getInputStream:&istream outputStream:nil];
[istream close];
NSLog(#"view is gone");
[super viewWillDisappear:animated];
}
- (void)downloadAgain{
NSInputStream *istream;
[camService getInputStream:&istream outputStream:nil];
[istream retain];
[istream setDelegate:self];
[istream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[istream open];
}
#pragma mark NSStream delegate method
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)event {
switch(event) {
case NSStreamEventHasBytesAvailable:
NSLog(#"Reading Stream");
if (![self currentDownload]) {
[self setCurrentDownload:[[NSMutableData alloc] initWithCapacity:409600]];
}
uint8_t readBuffer[4096];
int amountRead = 0;
NSInputStream * is = (NSInputStream *)aStream;
amountRead = [is read:readBuffer maxLength:4096];
[[self currentDownload] appendBytes:readBuffer length:amountRead];
//NSLog(#"case 1");
break;
case NSStreamEventEndEncountered:
[(NSInputStream *)aStream close];
UIImage *newImage = [[UIImage alloc] initWithData:[self currentDownload]];
[self setCurrentDownload:nil];
if(newImage != nil){
[imageView setImage:newImage];
}
[newImage release];
[self performSelector:#selector(downloadAgain) withObject:nil afterDelay:0.25];
break;
default:
break;
}
}
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
return YES;
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)dealloc {
[[self camService] release];
[[self currentDownload] release];
[super dealloc];
}
#end

Answer 1

I see that you call scheduleInRunLoop. In that case, when you don't need the stream, you should also call
[istream removeFromRunLoop:[NSRunLoop currentRunLoop]
forMode: NSDefaultRunLoopMode];
after you've closed the stream.

Answer 2

What is happening is whatever instance of the CameraViewer class (which is set to be the delegate) is being deallocated (causing EXC_BAD_ACCESS in the run loop) because you didn't retain it.
The solution is to either call retain on the CameraViewer class at instantiation, like so:
CameraViewer *cameraViewer = [[CameraViewer alloc] init];
[cameraViewer retain];