Is it possible to subclass NSSavePanel?

Question

I am wondering if there is a way to subclass NSSavePanel. Or if you were to create a dummy object, how would you mimic the beginSheetModalForWindow:CompletionHandler function of NSSavePanel?

-(void)beginSheetModalForWindow:(NSWindow *)window completionHandler:(void (^)(NSInteger *))handler{

I am blanking out on how to implement the block handler when implementing the function in the .m class file.

What are you actually trying to accomplish? Why do you want to subclass NSSavePanel? — Andrew Madsen, Oct 09 '13 at 20:09
Just working with a plugin that requires one to be returned. I mainly just want to recreate the beginsheetmodalforwindow from NSSavePanel. — Dan68am, Oct 09 '13 at 20:29
@Dan68am - What do you mean "how to implement the block handler"? If you write a method that takes a block then in the method you just call the block using standard function call syntax, you don't "implement" the block. — CRD, Oct 09 '13 at 23:48

CRD · Accepted Answer · 2013-10-10T17:16:27.793

Short Answer: No

Longer Answer: Here Be Dragons

It is possible but stuff will probably break. You can also add methods using a category and they might work, or they might not. The problems arise due to the way NSOpenPanel is implemented to support the App Sandbox - various chicanery is going on behind the scenes and even convenience category methods which just call existing methods on the class can result in errors being reported by OS X and dialogs not to appear. NSOpenPanel is a delicate creature that should be touched as little as possible and only ever with great care.

Wrapping an NSOpenPanel instance in another class is a different story and should not upset it at all. Go that route.

Addendum re: Comment

The declaration of beginSheetModalForWindow is:

- (void)beginSheetModalForWindow:(NSWindow *)window completionHandler:(void (^)(NSInteger result))handler

The completion handler gets passed a value indicating which button was pressed. To take action dependant on that you can use a standard if:

NSOpenPanel *openPanel;
NSWindow *hostWindow;
...
[openPanel beginSheetModalForWindow:hostWindow
                  completionHandler:^(NSInteger returnCode)
                                    {
                                       if (returnCode == NSFileHandlingPanelOKButton)
                                       {
                                          // OK pressed
                                          ...
                                       }
                                       else
                                       {
                                          // Cancel pressed
                                          ...
                                       }

                                    }
];

I will check this as the answer because you have answered the general question. I think I do not have a good understanding of block methods as arguments which is my problem. I want the completion handler to do something when a Cancel button is pressed, or NSOKButton. So `if(handler == NSOKButton){` do something. — Dan68am, Oct 10 '13 at 15:01
Thank you for the in depth answer. Helps me understand this much better — Dan68am, Oct 11 '13 at 14:38
@iOSCalendarpatchthecode.com – you can *customize* the standard open/save dialogs by adding a [custom view](https://developer.apple.com/documentation/appkit/nssavepanel/1525544-accessoryview?language=objc). What you can't easily do is *subclass* them and change the behavior - this disallowed to protect the sandbox restrictions. — CRD, Oct 25 '19 at 11:21
ok. I was a bit vague, I meant customize it to do something as simple as this https://stackoverflow.com/questions/58550993/nssavepannel-how-to-restrict-user-to-only-save-one-one-set-directory — Just a coder, Oct 25 '19 at 13:36

Is it possible to subclass NSSavePanel?

1 Answers1