How do I read Objective C methods - objective-c

Question

I think the biggest problem I'm having with understanding programming is understanding what a particular method does. For example
- (BOOL)tableView:(NSTableView *)aTableView shouldEditTableColumn:(NSTableColumn *)aTableColumn row:(NSInteger)rowIndex
When I look at the above method I know that it returns a boolean and that the method receives the following.
NSTableView
NSTableColumn
NSInteger
However, I don't understand what I need to provide to use the method correctly.
Do I just return a boolean?

Answer 1

It comes down to a saying: code tells you how, comments tell you why.
If you are writing a method, you need to know why you want the method and document it accordingly, a.k.a. comments. If you are overriding a method, then you would hope the producer of the method would document about what the method does.
If you're diving into iPhone development without a bit of programming background, you should at least read up the Introduction to The Objective-C Programming Language. If you want to find out what a particular method does in your code, you can always right click the method name and choose "Find Text in Documentation" to read more about it.

Answer 2

This method will be called by the table (or something) on your delegate (the class you are implementing this method in) when the table needs to know if a certain row and column can be edited. You just need to return YES or NO to indicate if you want to let it be edited.
This is an example implementation:
-(BOOL)tableView:(NSTableView *)aTableView shouldEditTableColumn:(NSTableColumn *)aTableColumn row:(NSInteger)rowIndex {
return NO;
}
This will mean the table can never be edited.
A more complex implementation like this would let only the first row be editable:
-(BOOL)tableView:(NSTableView *)aTableView shouldEditTableColumn:(NSTableColumn *)aTableColumn row:(NSInteger)rowIndex {
if (rowIndex == 0)
return YES;
else
return NO;
//This can be shortened to:
//return rowIndex == 0;
}

Answer 3

The name of the method tableView:shouldEditTableColumn:row: should give you a clue that it is about editing rows and columns in a table view. You could probably guess that, since it is returning a boolean it's called to determine with a table view should edit the supplied row of the supplied column. However, that would just be a guess, so at this point (if I hadn't been using that method only yesterday and thus know exactly what it is for) I would start googling for it (or using Xcode search if I had access to Xcode).
A useful tip for Googling Cocoa documentation is to search only on site:developer.apple.com so we'll try site:developer.apple.com tableView:shouldEditTableColumn:row:. The top hit in this case is NSTableViewDelegate which is the one we want.