Open Radar

 
Since the new addition of blocks to Objective-C in Snow Leopard, many Foundation/AppKit classes have added new methods that use a "completion handler" block as a callback, rather than the old method of passing a delegate, a callback selector, and a contextInfo parameter.  

For example, in 10.6, NSSavePanel now has a method: 

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

which replaces the old method

- (void)beginSheetForDirectory:(NSString *)path file:(NSString *)name modalForWindow:(NSWindow *)docWindow modalDelegate:(id)modalDelegate didEndSelector:(SEL)didEndSelector contextInfo:(void *)contextInfo method.

However, no such method exists to replace the NSApplication method:

- (void)beginSheet:(NSWindow *)sheet modalForWindow:(NSWindow *)docWindow modalDelegate:(id)modalDelegate didEndSelector:(SEL)didEndSelector contextInfo:(void *)contextInfo  

I would like to see a method along the lines of:

- (void)beginSheet:(NSWindow *)sheet modalForWindow:(NSWindow *)docWindow completionHandler:(void (^)(NSInteger result))handler

that would allow using custom sheets without having to resort to the clunky setup of implementing a callback selector and passing around a contextInfo parameter.