CODEWITHSUNDEEP
iosxcodeswiftoption-type
rb612
rb612

Reputation: 5563

Why can we explicitly unwrap this optional without worrying about a crash?

I was watching this video and at the 2 minute mark he explains somehting that I really don't understand.

Code:

class Order {
    var product: Product?
}

class Product {
    var order: Order?
}

var myOrder = Order()
var iPhone6 = Product()

myOrder.product = iPhone6
myOrder.product!.order = myOrder

He says, when talking about the explicit unwrapping, that if the property is null, the statement won't crash and get a null reference. He says the statement will have no effect if the product happens to be nil upon explicit unwrapping. I thought this was the case with using the question mark, like myOrder.product?.order, but NOT with the exclamation point.

Upvotes: 0

Views: 182

Answers (1)

Vasil Garov
Vasil Garov

Reputation: 4921

Straight to your question - here you are sure about creating your Order instance so you don't have to check for nil. But in other cases you will have to check for nil.

What bothers me here is that you will have a retain cycle. So what you can make to avoid retain cycles is to keep weak reference to the Order instance inside your Product class (an order should always have a product but a product can go without an order). Something like this:

class Product {
    weak var order: Order?
}

Upvotes: 2

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