Objective C convention: When to use For and when to use With

Question

According to the Apple guideline , seems it is confusing, e.g. for method viewWithTag

In Java, I would have a method called

getViewByTag // Java version, equivalent to viewWithTag in Obj-C

But I also found there are some method like objectForKey, so why not just use objectWithKey instead?

getObjectByKey or just get // Java version, equivalent to objectForKey, 
                           // but why not objectWithKey? Or not viewForKey above?

Answer 1

I actually think it is much simpler than what most answers think. I think it has less to do with complex programming language specifics, and has more to do with the uniqueness of the object in question.

When you say viewWithTag:, you are asking the UIView for any view that has that tag. There might be several. The UIView will return one of 'em.

However, objectForKey: (to me) sounds like there should be a single object (or nil) associated with that key. So, the key kinda exists and is bound (tightly coupled) to a single object.

EDIT:

There is an answer mentioning the existence of "by", which further implies how the convention has nothing to do with programming language complexities. It's just natural English.

NSString's stringByAppendingString:, for example, uses by, only because the function is written with a the verb appending. You can't say withAppending, that's bad English.

Answer 2

From my observation

While setting/getting the objects, you use WITH.

e.g. For setting of NSMutableArray object

 - (id)initWithCapacity:(NSUInteger)numItems

While setting/getting the properties for objects, you use FOR.

e.g.For setting value for property of type NSMutableDictionary

- (void)setValue:(id)value forKey:(NSString *)key

Hope this helps in clearing your doubt