Cocoa -Touch: executeSelectorOnMainThread: weird behavior + crash

Question

I have a situation where I am lazy to upload images from www.
This is a list of elements, when one element is listened, a detailed view is transferred to the navigation controller.

In this detailed view, the element has an image, which is first the default image, and I want to start downloading the image from the URL.

So, I create an object that, after initialization, separates a new stream, which in turn loads the content, and then notifies my idea that the data is loaded:

// in MyLoader:
- (MyLoader *)initWithUrl:(NSURL *)url requester:(id)requester {
    self.url = url;
    self.requester = requester; // both are nonatomic, retain properties
    [self performSelectorInBackground:@selector(loadIt) withObject:nil];
}

- (void)loadIt {
    NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init];
    NSData *data = [NSData dataWithContentsOfURL:url];
    [requester performSelectorOnMainThread:@selector(dataReady) withObject:data waitUntilDone:YES;
    [arp release];
}

// in MyRequester:
- (void)somewhere {
    MyLoader *loader = [[[MyLoader] alloc] initWithUrl:someUrl requester:self] autorelease];
    // then I retain loader somewhere, it more complicated but I have verified that it properly retained.
}

A few notes:

• , . performSelectorOnMainThread , data requester .

• , NSData , withObject:nil. - .

• , . waitUntilDone:YES, requester dataReady. performSelectorOnMainThread ( ), dataReady. BTW, - (void)dataReady:(NSData*) int x = 1; ( ). , waitUntilDone:NO, .

• ( ), .

- , ?

, , , [requester performSelectorOnMainThread..., .

, , .

#0  0x00a71004 in ___TERMINATING_DUE_TO_UNCAUGHT_EXCEPTION___ ()
#1  0x93436e3b in objc_exception_throw ()
#2  0x0028aca6 in __NSThreadPerformPerform ()
#3  0x00a098e1 in CFRunLoopRunSpecific ()
#4  0x00a08c48 in CFRunLoopRunInMode ()
#5  0x0005a78d in GSEventRunModal ()
#6  0x0005a852 in GSEventRun ()
#7  0x0168a003 in UIApplicationMain ()
#8  0x000028d4 in main (argc=1, argv=0xbffff100) at /Users/myName/Document/appName/main.m:14

Answer 1

:

[requester performSelectorOnMainThread:@selector(dataReady) withObject:data waitUntilDone:YES;

:

[requester performSelectorOnMainThread:@selector(dataReady:) withObject:data waitUntilDone:YES;

: @selector (dataReady:) ( ) , , :

- (void) dataReady:(NSData *)theData ...