SwiftUI ForEach get element AND index in 2d array

Question

I need to access the index as well as the element in a ForEach loop.

So far, I have in my data store:

@Published var sevenDayReview: [[CGFloat]] = [
        [1754,1654],[1854,1687],[1985,1854],[1765,1652],[1864,1698],[1987,1654],[1865,1465]
    ]

and in my view:

ForEach(self.dataModel.sevenDayReview, id: \.self) { array in
       ForEach(array, id: \.self) { element in
             VStack {
                    ReviewChart(dataModel: CalorieViewModel(), valueHeight: element, cornerRadius: 5, color: 2 )
              }
       }
}

which is working fine. But I want to pass the current array index of the current element to the color parameter.

Background: Load a bar chart with values from the datastore and alternate the colors by row index.

I can't figure out what the best way to do this is in SwiftUI.

iSpain17 · Accepted Answer · 2020-01-14 13:39:51Z

5

You can use a different init of the ForEach view:

ForEach(0..<array.endIndex) { index in //inner ForEach
    VStack {
        ReviewChart(dataModel: CalorieViewModel(), 
                    valueHeight: array[index], 
                    cornerRadius: 5, 
                    color: index)
    }
}

answered Jan 14, 2020 at 13:39

iSpain17

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5 Comments

wildfang Over a year ago

Thank you. I tried it and get the following error: "Cannot subscript a value of incorrect or ambiguous type". The compiler marks the array[index]

iSpain17 Over a year ago

You need to note that a lot of times you have different errors than what XCode shows you when dealing with SwiftUI. index is Int so this error should not be valid.

wildfang Over a year ago

You are right, I had to close XCode and restart, then clean the project and the error disappeared. Thank you!

Alessandro Mascolo Over a year ago

I receive a warning for a similar syntax: ForEach(0..<array.endIndex) "Non-constant range: argument must be an integer literal"

iSpain17 Over a year ago

@AlessandroMascolo add an id: \.self argument to your ForEach initializer if your array isn’t constant.

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