Question about code in SwiftUI tutorials

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Created Sep ’22

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I am novice at apple programming, the following code in SwiftUI tutorials is confusing to me , where can I find the explaination about the syntax?

In section 5,Make the List Dynamic

        List(landmarks, id: \.id) { landmark in
            LandmarkRow(landmark: landmark)
        }

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Answer 1

Claude31 OP

Sep ’22

Accepted Answer

That's the very purpose of the tutorial to explain syntax… But in some places, explanations are a bit short.

For this:

List(landmarks) { landmark in
                LandmarkRow(landmark: landmark)
}

you will list all items in landmarks (an array)
each item is identified in the closure by the landmark var
and you execute code that follows in keyword (refer to Swift Programming Language book in Apple Bookstore to get more details)
namely, you load the LandMarkRow for this landmark and display in the List.

Hope that helps.

0

Answer 2

darkpaw OP

Sep ’22

A List shows a row for each item you supply, in a single column:

List {
    Text("A List Item")
    Text("A Second List Item")
    Text("A Third List Item")
}

Because the example is using a list of Landmark objects, they have to be Identifiable, so there's an id parameter for each one.

The syntax is saying:

Go through each item in the set of Landmark objects: landmarks
Create a variable we can refer to when we're using each one: landmark
Add a row using the LandmarkRow view, and supply the current landmark to that view so the view can use the data.

In Xcode if you put your cursor onto a variable, you'll see where else that variable is used, so if you click on landmark on the first line of code you shared, it would be highlighted in the second line, too:

List(landmarks, id: \.id) { >->->landmark<-<-< in
    LandmarkRow(landmark: >->->landmark<-<-<)
}

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