How to define and call a method with multiple parameters [duplicate]

Question

Possible Duplicate:
How to write a method/message with multiple parameters?

I am really confused here... I have looked at SO and Google where I found an example of calling a method with two parameters. So I modified it for my use, and unfortunately I can't get it to work. Here is my updated code:

-  definition of method
- (NSArray *) fetchEventsBetweenDates: (NSDate *) sDate: andDate: (NSDate *) eDate;

- definitions and creation of sD and eD
    //  convert start dates to NSDate
    NSDateFormatter* df = [[NSDateFormatter alloc] init];
    [df setDateFormat:@"MM/dd/yyyy"];
    NSDate* sD = [df dateFromString:@"10/03/2012"];
    NSLog(@"startDate: %@", sD);

    //  convert end dates to NSDate
    NSDate* eD = [df dateFromString:@"10/05/2012"];
    NSLog(@"endDate: %@", eD);

- call to method
    [self.eventsList addObjectsFromArray:[self fetchEventsBetweenDates: sD andDate: eD]];

- method
- (NSArray *) fetchEventsBetweenDates: (NSDate *) sDate: andDate: (NSDate *) eDate  {

I have tried every permutation I think was reasonable, and it still will not build. I am getting a "expected ':' on the call to the method.

What am I doing wrong?

Answer 1

Please read The Objective-C Programming Language from Apple. Specifically the Message Syntax part.

The message declaration syntax is like this:

- (return type)myMethodParam1:(param1 type)p1 param2:(param2 type)p2;

Example:

- (NSArray *)fetchEventsBetweenDate:(NSDate *)startDate andDate:(NSDate *)endDate;

The implementation is the same, you just replace the semicolon ; with the implementation in curly brackets { implementation }.

When calling a method, you replace the parameter declarations with your variables:

// Assuming aDate and otherDate exist.
[self fetchEventsBetweenDate:aDate andDate:otherDate];

Answer 2

Start with a basic Objective-C book. Pretty clear you don't understand the syntax or language yet (no big deal -- we all started there).

If you really had a method defined as:

- (NSArray *) fetchEventsForADay: (NSDate *) sDate: (NSDate *) eDate;

You would call it using [someObj fetEventsForADay: date1 : date2]; That would suck; the whole point of Objective-C's interleave-arguments-with-method-name pattern is to make APIs self documenting. Thus, you'd probably want:

• (NSArray ) fetchEventsBetweenStartDate:(NSDate) sDate andEndDate:(NSDate*) eDate;

Which would be called like [someObj fetchEventsBetweenStartDate: date1 andEndDate: date2];. Much clearer.