Add a sections on protocols about objective-c-style-guide HOT 2 CLOSED

I'll throw one random quirk of mine into the mix for debate: when creating delegate protocols, I generally like to pass the object backward to the delegate. I do this for two reasons: first, it makes it clear in the client why that method is there, so someone doesn't think it's just a local method and refactors/deletes willy nilly. Second, I'm never sure what the client (or a future client) might need.

For example, from recent work on our internal ad framework:

@class NMAdView; 
@protocol NMAdViewDelegate <NSObject>
- (UIViewController *)viewControllerForAdView:(NMAdView *)adView;

@optional
- (BOOL)adViewShouldExpand:(NMAdView *)adView;
- (void)adViewDidExpand:(NMAdView *)adView;
- (void)adViewDidCollapse:(NMAdView *)adView;
@end

from objective-c-style-guide.

I agree this is good practice. It follows from Apple's conventions, eg, tableView:didSelectRowAtIndexPath:. To point out what most people probably already realize, an object can be the delegate of multiple other objects of the same class. In the case of tableView:didSelectRowAtIndexPath:, if tableView was not passed in, the receiver would have no way of knowing whether this message was sent by the main table view, or perhaps a search table view who's delegate is the same object as the main table view.

from objective-c-style-guide.