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Scroll fast using pure SwiftUI

Swift 100.00%

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plivesey chouti-dev my-swift-lab

collectionthing's Issues

The view doesn't update when data changes

This can be shown by the following code. When tapping on increment, the view doesn't update. This because visible rows isn't updated so it's still showing old data.

I've fixed this in #2

struct ContentView: View {

    @State var data = [1, 2, 3, 4, 5, 6, 7, 8, 9]

    var body: some View {
        VStack {
            Button(action: incrementData) {
                Text("Increment")
            }

            Button(action: insert) {
                Text("Insert")
            }

            FastCollection(items: data, itemHeight: 60) { number in
                Text("\(number)")
                    .frame(height: 60)
            }
        }
    }

    func incrementData() {
        data = data.map { $0 + 1 }
    }

    func insert() {
        data.insert(Int.random(in: data[8]+1..<100), at: 5)
    }
}

extension Int: Identifiable {
    public var id: Int {
        return self
    }
}

Modifying state during view update, this will cause undefined behavior.

I got this runtime warning while running the code. I got this for one of my other preference changes. The only way I could get rid of this warning was to to add a DisapatchQueue.main.async which I know you don't want to do.

It seems to occur whenever the view changes because of an observed object changing. I haven't tried to reproduce this yet.