Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Object-Oriented Objective-C Memory, Arrays and Loops, Oh My! Immersive Example - Gabe's KFC

Salar Kohnechi
Salar Kohnechi
3,171 Points
Posted by Salar Kohnechi
Salar Kohnechi
3,171 Points

Confused about the structure of orderArray

Hi, in this example I'm a bit unsure why we are repeating items in the array so many times and the logic of how it's structured. Can anyone provide a more in-depth explanation?

How do we go from this:

Chicken Bucket - Price $10.00, cost $3.75
Chicken Sandwich - Price $3.25, cost $1.25
Soda - Price 2.00, cost $0.25

Family Deal - 1 Bucket, 4 Sodas - Price $15.00, cost $4.75
Double Trouble - 2 Sandwiches, 2 Sodas - Price $9.50, cost $4.50
Lonely Bird - 1 Sandwich, 1 Soda - Price $5.00, cost $1.50

East side profit = $710

To this:

NSArray *orderArray = @[ @(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda),@(Soda), @(Sandwich), @(Sandwich), @(Bucket), @(FamilyDeal), @(Sandwich), @(DoubleTrouble), @(LonelyBird), @(DoubleTrouble), @(Soda)];

1 Answer

miikis
miikis
44,957 Points
miikis
miikis
44,957 Points

Hi Salar,

In this course, Gabe uses an Objective-C data structure called an enum to model the menu-items. The reason he chose to do it this way is mainly to avoid syntax errors by taking advantage of the compiler's error-handling system. In other words, we could have just as easily made the elements of the orderArray a bunch of NSString objects like "Sandwich," "Lonely Bird" etc. but then we'd have to manually spell-check the syntax since the compiler wouldn't know what was right and what was wrong; that is, the compiler wouldn't know that "Loooooney Bird" is wrong and "Lonely Bird" is right. If we use an enum, however, we only have to make sure we spell things right once, in the enum declaration.

Anyway, as it stands, orderArray contains a bunch of OrderItems (the name of the enum) in an arbitrary order that was pre-selected by Gabe. After that we loop through the array, and for each element in the array, we update the revenueTotal and costTotal with the summation of the appropriate price and cost . Finally, we store the difference between revenueTotal and costTotal as the profit in a variable aptly named profit.