Why is prepareWithInvocationTarget: specific to NSUndoManager?

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NSInvocation* invocation = [NSInvocation invocationWithMethodSignature:[performer methodSignatureForSelector:@selector(playFile:)]];
[invocation setSelector:@selector(playFile:)];
[invocation setTarget:performer];
NSString* string = [NSString stringWithString:@"reverse.wav"];
[invocation setArgument:&string atIndex:2];

...with...

NSInvocation* invocation = [[NSInvocation prepareWithTarget:performer] playFile:@"reverse.wav"];

. Why isn't such a method implemented?

You can make your code cleaner by using a variable for the selector `SEL sel = @selector(playFile:)`, which also avoids mistyping long selector names, and by just setting `NSString* string = @"reverse.wav"` - the `-stringWithString:` call is unnecessary. — Jeremy W. Sherman, Oct 27 '10 at 17:23

score 2 · Accepted Answer · answered Oct 27 '10 at 17:20

2

It just isn't, but there is no shortage of third-party implementations of the same functionality, such as the one written up at and created for Cocoa with Love.

answered Oct 27 '10 at 17:20

Jeremy W. Sherman

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So strange that it isn't there; I thought there'd be a reason. Great link! – andyvn22 Oct 27 '10 at 17:34
@andyvn22: People just don't create NSInvocations all that much, so a nicer way to do it probably isn't very high on Apple's to-do list. – Chuck Oct 27 '10 at 20:31
Besides, we have blocks now. Finally :) – Mike Abdullah Oct 27 '10 at 21:19

Why is prepareWithInvocationTarget: specific to NSUndoManager?

1 Answers1