CODEWITHSUNDEEP
objective-c
kubusabadi
kubusabadi

Reputation: 132

How to initiate NSArray with objects passed by method with variable argument list

Is it possible to do that this way:

- (void) setList:(id) firstObj,...
{
    va_list args;
    va_start(args,firstObj);
    list = [[NSArray alloc] initWithObjects:args]; // Compile error
    va_end(args);
}

Upvotes: 3

Views: 1849

Answers (3)

user529758
user529758

Reputation:

Try this:

- (void) setList:(id)firstObj, ... NS_REQUIRES_NIL_TERMINATION
{
    va_list args;
    va_start(args, firstObj);
    list = [[NSMutableArray alloc] initWithObjects:firstObj, nil];
    id obj;
    while ((obj = va_arg(args, id)) != nil) {
        [list addObject:obj];
    }
    va_end(args);
}

Upvotes: 7

ColdLogic
ColdLogic

Reputation: 7275

Pretty close, something like this should work. The problem is that there isn't an API function for this, so you have to get the objects out of the list and add them to an array your instantiate.

-(void *)setList:(id)firstObj, ... {
    //The array you're holding everything in
    arr = [NSMutableArray array];
    [arr addObject:firstObject];

    //Get the variable list
    va_list args;
    va_start(args, action1);

    //Create the object
    id object = va_arg(args, id);

    //Keep adding objects until you run out
    while(object) {
        [arr addObject:object];
        object = va_arg(args, id);
    }

    va_end(args);
}

Upvotes: 2

Joe
Joe

Reputation: 57179

NSArray does not have a constructor that takes a va_list so you will have to loop over the args yourself and add them to a mutable array. You should also add a constraint for the arguments to be nil terminated.

- (void) setList:(id) firstObj,... __attribute__((sentinel)) //make sure it is nil terminated
{
    //You have to add the first object yourself
    NSMutableArray *tmplist = [NSMutableArray arrayWithObject:firstObj];
    va_list args;
    va_start(args,firstObj);

    id arg; 
    while((arg = va_arg(args, id)) != nil)
        [tmplist addObject:arg];

    va_end(args);

    list = [tmplist copy];
}

Upvotes: 5

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