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SOLVED: Day 33 - Showing and hiding views with transitions. Question about Views in if-statements

Forums > 100 Days of SwiftUI
@diopermanganato  

Shouldn't the following code be not allowed?

if isShowingRed {
    Rectangle()
        .fill(Color.red)
        .frame(width: 200, height: 200)
}

Here https://www.hackingwithswift.com/books/ios-swiftui/conditional-modifiers it's said "some View means one specific type of View will be returned, but we don’t want to say what". Since the if statement ensures that there are different returns depending on the value of isShowingRed this can't run, or can he?

2      

@roosterboy  HWS+

Since the if statement ensures that there are different returns depending on the value of isShowingRed this can't run, or can he?

There actually aren't different return types.

If you take some SwiftUI code like this:

    var body: some View {
        VStack {
            Rectangle()

            if showTwoRects {
                Rectangle()
            }
        }
    }

and check its type, you will find that it is:

VStack<TupleView<(Rectangle, Optional<Rectangle>)>>

So regardless of whether the second Rectangle is shown or not, the type is still the same because the conditional is incorporated into the type. The type is the same, even if what is actually displayed on screen is different.

2      

@diopermanganato  

So whenever there are Views inside an if statement they are wrapped in an Optional<View>, aren't they?

2      

@roosterboy  HWS+

Yep, if it's a simple if. If it's an if else, the two branches go into a _ConditionalContent:

        VStack {
            Rectangle()

            if twoRects {
                Rectangle()
            } else {
                RoundedRectangle(cornerRadius: 8)
            }
        }
VStack<TupleView<(Rectangle, _ConditionalContent<Rectangle, RoundedRectangle>)>>

2      

@diopermanganato  

Thank you, now it's all clear

2      

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