How to increment a state in a ForEach loop in SwiftUI? - swift

Question

I need to increment the genNum variable and pass it to another struct in a ForEach loop. My code is compiling properly but cannot preview it in the simulation as well as the canvas. Getting "cannot preview in this file". Another error I am getting is "RemoteHumanReadableError: The operation couldn’t be completed. (BSServiceConnectionErrorDomain error 3.)".
BSServiceConnectionErrorDomain (3):
==BSErrorCodeDescription: OperationFailed
import SwiftUI
#available(iOS 14.0, *)
struct CategoryView: View {
#State var genNum: Int = -1
var categories: [Int: [PokemonData]] {
Dictionary(
grouping: pokemonData,
by: { $0.generation }
)
}
var columns: [GridItem] = [
GridItem(.fixed(170)),
GridItem(.fixed(170))
]
var body: some View {
NavigationView {
ScrollView {
LazyVGrid(columns: columns) {
ForEach(categories.keys.sorted(), id: \.self) { key in
CategoryCard(genNum: self.increment()) // <--- Having problem with this line
}
}
AllCard()
.padding(.horizontal, 15)
.padding(.bottom, 20)
}
.navigationTitle("Categories")
}
}
// Function to increment the state value
func increment() -> Int {
self.genNum += 1
let i = genNum
return i
}
}

Answer 1

If all you want to do is to pass values from 0 to count-1 to your CategoryCard() initializer, you can use the enumerated() function. That function takes an array as input and returns an array of tuples where the first item is an array index and the 2nd item is the the element from the original array.
This code, for example:
let array = ["zero", "one", "two", "three"]
array.enumerated().forEach { (index, string) in
print (index, string)
}
Outputs the following:
0 zero
1 one
2 two
3 three
So you could rewrite your code like this:
LazyVGrid(columns: columns) {
ForEach(categories.keys.sorted().enumerated(), id: \.self) { (index, key) in
CategoryCard(genNum: index) // <--- Having problem with this line
}
}
(Disclaimer: I haven't used SwiftUI yet, so I'm not totally clear on what ForEach is doing inside your LazyGrid)