How do I get the contextInfo in beginSheetModalForWindow:completionHandler:? - objective-c

Question

I want to transition all my old usages of -beginSheetModalForWindow:modalDelegate:didEndSelector:contextInfo: to the recommended -beginSheetModalForWindow:completionHandler:. How do I define contentInfo: and get it in the completionhandler?
Here is an example of how the old code looks like:
[alert beginSheetModalForWindow:window
modalDelegate:self
didEndSelector:#selector(alertDidEnd:returnCode:contextInfo:)
contextInfo:(void *)CFBridgingRetain(fc)];
The endSelector method looks like this:
- (void)alertDidEnd:(NSAlert *)alert returnCode:(int)returnCode contextInfo:(void *)contextInfo
{
if (returnCode == NSAlertDefaultReturn)
{
FileController *fc = (__bridge FileController *)(contextInfo);
[...]
}
}
}
I guess the new method should look somewhat like this:
[alert beginSheetModalForWindow:window completionHandler:^(NSModalResponse alertReturnCode)
{
if (alertReturnCode == NSAlertFirstButtonReturn)
{
// evaluate contextInfo here ...
}
}];
But I have no clue how to get the contextInfo into the completionhandler.
Any help is appreciated.

Answer 1

There is no context info because the completion handler block can simply look right at the surrounding environment.
NSString* s = #"heyho";
[alert beginSheetModalForWindow:window completionHandler:^(NSModalResponse alertReturnCode) {
if (alertReturnCode == NSAlertFirstButtonReturn)
{
// s is visible here
}
}];
In other words, we don't need to pass a context because we are in a context. If you have a FileController to pass down into the block, just let it pass down into the block.