Using NSUndoManager with prepareWithInvocationTarget, Gestures and Objects

问题

I have a Drawing App of sorts. I want to Implement Undo/Redo. Though I'm running into difficulty with storing the Original and New Values for the Undo/Redo.

With Gestures I need to store a Few things: transform, Center, for the Properties Dialog, I need to store many more, Color, Font, Font-Size, Outline, Outline Color, the Text It self, etc.

I've created a NSMutableDictionary of the Attributes that the user can change in a Single Gesture/Properties Popover.

I wanted to use Rob's Answer for NSUndoManager and Rotation Gesture though using his Solution works with CGAffineTransform, which when sent as a parameter for the prepareWithInvocationTarget, its not an object and just puts a copy of the CGAffineTransform struct on the Undo/Redo stack.

Though when using the prepareWithInvocationTarget with my NSMutableDictionary the Dictionaries I'm passing in (OriginalAttribs, newAttribs) are not retained. I cannot have them as local iVars as they will change with each action on a drawing object.

Seems like I want to use retainArguments as part of NSInvocation though I don't really want to retain them. I need a copy of them.

Its the Gestures that make this Difficult as I can't keep setting the OrigianlCenter, OriginalTransform as it changes while the gesture is active.

UPDATE I found this link and it seems to be similar to what I want to do.

I setup my NSUndoManager like this:

        //Needed to get access to UndoManager
    NSUndoManager * undoManager = [(IoScreenEditorViewController * )UIAppDelegate.ioMainViewController.currentViewController undoManager];

        //Need to Store our Center as a NSValue
    [undoManager prepareWithInvocationTarget:self];
    [undoManager forwardInvocation:anInvocation ];

I then get a runtime error:

 -[NSUndoManager undoAttributesWithOriginalAttributes:newAttributes:]: unrecognized selector sent to instance 0xeedcbd0

undoAttributesWithOriginalAttributes:newAttributes: is the selector that I setup for my NSInvocation Object. According to the Documentation here, it says that it should pass it along to self (the Target), not the undo manager self?

来源：https://stackoverflow.com/questions/9793078/using-nsundomanager-with-preparewithinvocationtarget-gestures-and-objects

标签

objective-c

ios

nsundomanager

nsinvocation