MyDocument.m

@implementation MyDocument

- (void)dealWithCompressionFinished:(TextureAtlas *)ta
{
    [textureController closeCompressingSheet];
    
	if (nil == [ta previewImage])
	{
		[[NSAlert alertWithMessageText:@"Invalid Texture"
						 defaultButton:@"OK"
					   alternateButton:nil
						   otherButton:nil
			 informativeTextWithFormat:@"Textures must be square, have a power of two number of pixels high/wide and be at least 8 pixels high and wide"]
		 beginSheetModalForWindow:[self windowForSheet]
		 completionHandler:^(NSInteger result){}];
	}
}

@end

NSAlertWithBlocks.m

#import "NSAlertWithBlocks.h"

@interface NSAlert (WithBlocksPrivate)

- (void)alertDidEnd:(NSAlert *)alert returnCode:(NSInteger)returnCode contextInfo:(void *)contextInfo;

@end


@implementation NSAlert (WithBlocks)

- (void)beginSheetModalForWindow:(NSWindow *)window completionHandler:(void(^)(NSInteger result))completionHandler
{
	[self beginSheetModalForWindow:window modalDelegate:self didEndSelector:@selector(alertDidEnd:returnCode:contextInfo:) contextInfo:[completionHandler copy]];
}

- (void)alertDidEnd:(NSAlert *)alert returnCode:(NSInteger)returnCode contextInfo:(void *)contextInfo
{
	void(^handler)(NSInteger result) = (void(^)(NSInteger result))contextInfo;
	
	handler(returnCode);
	
	[handler release];
}

@end

Stack

#0	0x00007fff9836f5b6 in fsync ()
#1	0x00007fff91e23641 in -[CFXPreferencesPropertyListSourceSynchronizer writePlistToDisk] ()
#2	0x00007fff91dec355 in -[CFXPreferencesPropertyListSourceSynchronizer synchronizeAlreadyFlocked] ()
#3	0x00007fff91dec0b2 in -[CFXPreferencesPropertyListSourceSynchronizer synchronize] ()
#4	0x00007fff91debd3c in -[CFXPreferencesPropertyListSource synchronize] ()
#5	0x00007fff91e19752 in -[CFXPreferencesSearchListSource synchronize] ()
#6	0x00007fff91e21aa1 in ___CFXPreferencesAppSynchronize_block_invoke_1 ()
#7	0x00007fff91deb0f0 in ____CFXPREFS_SYNC_LOCKED_block_invoke_1 ()
#8	0x00007fff94543afd in _dispatch_barrier_sync_f_invoke ()
#9	0x00007fff91e21a44 in CFPreferencesAppSynchronize ()
#10	0x00007fff984e2ff9 in TalkingAlertsEnabled ()
#11	0x00007fff93229954 in -[NSAlert startTimerForSpeaking] ()
#12	0x00007fff9322adc2 in -[NSAlert beginSheetModalForWindow:modalDelegate:didEndSelector:contextInfo:] ()
#13	0x000000010001bf00 in -[NSAlert(WithBlocks) beginSheetModalForWindow:completionHandler:] at /Users/tatd2/Documents/HuntedCow/My/Classes/CocoaExtensions/NSAlertWithBlocks.m:22
#14	0x0000000100005519 in -[MyDocument dealWithCompressionFinished:] at /Users/tatd2/Documents/HuntedCow/My/Classes/Editor Controllers/MyDocument.m:434
#15	0x00007fff91e3611d in -[NSObject performSelector:withObject:] ()
#16	0x00007fff96c36830 in __NSThreadPerformPerform ()
#17	0x00007fff91db5241 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#18	0x00007fff91db4aad in __CFRunLoopDoSources0 ()
#19	0x00007fff91ddb8d9 in __CFRunLoopRun ()
#20	0x00007fff91ddb216 in CFRunLoopRunSpecific ()
#21	0x00007fff909a94ff in RunCurrentEventLoopInMode ()
#22	0x00007fff909b0c21 in ReceiveNextEventCommon ()
#23	0x00007fff909b0aae in BlockUntilNextEventMatchingListInMode ()
#24	0x00007fff92f82191 in _DPSNextEvent ()
#25	0x00007fff92f81a95 in -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] ()
#26	0x00007fff92f7e3d6 in -[NSApplication run] ()
#27	0x00007fff931fc52a in NSApplicationMain ()
#28	0x00000001000c52a2 in main at /Users/tatd2/Documents/HuntedCow/My/editorMain.m:13