Objective-C if else function, need to iterate from array, but Xcode is throwing undeclared errors

Question

The code is supposed to be a basic objc program that contains a list of purchased stocks, foreign and domestic. Right now, I have to put them into a portfolio and sum it up. I realized that I could not sum them up because I was getting an error with my BNRForeign header and implementation files. For the rest of the code, please see here (my other question that was answered): Trying to create a portfolio of stocks with a total value in Objective-C, but unsure of the approach

So I'm working on some code for a stock problem from a book that I'm reading, which was partly answered in another question I posted yesterday. I have an entirely new question branching from that now.

For my if condition, I want to iterate through an array, but I'm not sure how to implement this.

My main.m:

int main(int argc, const char * argv[]) {
    @autoreleasepool {

        BNRStockHolding *stock0 = [[BNRStockHolding alloc]init];
        BNRStockHolding *stock1 = [[BNRStockHolding alloc]init];
        BNRStockHolding *stock2 = [[BNRStockHolding alloc]init];
        BNRForeignStockHolding *stock3 = [[BNRForeignStockHolding alloc]init];

        stock0.purchaseSharePrice=2.30;
        stock0.currentSharePrice=4.50;
        stock0.numberOfShares=40;

        stock1.purchaseSharePrice=12.19;
        stock1.currentSharePrice=10.56;
        stock1.numberOfShares=90;

        stock2.purchaseSharePrice=45.10;
        stock2.currentSharePrice=49.51;
        stock2.numberOfShares=210;

        stock3.purchaseSharePrice=43.05;
        stock3.currentSharePrice=28.31;
        stock3.numberOfShares=15;

        NSMutableArray *stocks = [NSMutableArray arrayWithObjects:stock0, stock1, stock2, stock3, nil];
        for (BNRForeignStockHolding *s in stocks) {
            float a = s.purchaseSharePrice;
            float b = s.currentSharePrice;
            int c = s.numberOfShares;
            float d = s.costInDollars;
            float e = s.valueInDollars;
            float f = s.foreignCostInDollars;
            float g = s.foreignValueInDollars;

            if () {
                NSLog(@"\n Purchase Price: %.2f\n Current Price: %.2f\n Number of Shares %d\n Cost in Dollars %f\n Value in Dollars %f\n", a, b, c, d, e);
            }
            else {
                NSLog(@"\n Purchase Price: %.2f\n Current Price: %.2f\n Number of Shares %d\n Cost in Dollars %f\n Value in Dollars %f\n", a, b, c, f, g);
            }

            }
    }
    return 0;
}

Basically, for stock0, stock1, and stock2, I need NSLog to apply functions a, b, c, d, e. For stock3, I need NSLog to apply functions a, b ,c, f, g.

I tried things like this:

if (stock(i), i=0, i<=2) {

NSLog(@"etc", a, b, c, d, e);
}
else {
NSLog(@"etc", a, b, c, f, g);
}

Xcode keeps stating that stock(i) and i are undefined implicit functions and that they are undeclared. I understand this, but since I am new to programming, I am unsure of how to define them so that I may iterate through my array.

Thanks for your help!

Answer 1

Your for has to look like that:

    for (BNRStockHolding * s in stocks) {
      //Common assingments
      if([s isKindOfClass:[BNRForeignStockHolding class]]){
          BNRForeignStockHolding * aux = (BNRForeignStockHolding*)s;
          float f = aux.foreignCostInDollars;
          float g = aux.foreignValueInDollars;
          NSLog(@"\n Purchase Price: %.2f\n Current Price: %.2f\n Number of Shares %d\n Cost in Dollars %f\n Value in Dollars %f\n", a, b, c, d, e);
      } else if([s isKindOfClass:[BNRStockHolding class]]){
          NSLog(@"\n Purchase Price: %.2f\n Current Price: %.2f\n Number of Shares %d\n Cost in Dollars %f\n Value in Dollars %f\n", a, b, c, f, g);
      }
   }

Answer 2

Generalising, your question is not really "do something for stock3" but rather "do something based on whether the stock is an instance of BNRForeignStockHolding or not".

When you have an instance of a class you can test if it is a particular class using the method isMemberOfClass: (note: there is a related method isKindOfClass: which tests for a being a class or any of its subclasses).

So you can test if s is an instance of BNRForeignStockHolding using:

[s isMemberOf:[BNRForeignStockHolding class]]

Using this you can rewrite your code to use just two variables, d and e, setting them according to the type of s:

float d, e;
if ([s isMemberOf:[BNRForeignStockHolding class]])
{
   // BNRForeignStockHolding
   d = s.foreignCostInDollars;
   e = s.foreignValueInDollars;
}
else
{
   // BNRStockHolding
   d = s.costInDollars;
   e = s.valueInDollars;
}

and now you can just use the variables a, b, c, d and e and it does not matter which, if any, of your stocks are foreign the code will work.

HTH