ios-mail/Modules/InboxCoreUI/Sources/View+OnLoad.swift

// Copyright (c) 2024 Proton Technologies AG
//
// This file is part of Proton Mail.
//
// Proton Mail is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Proton Mail is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Proton Mail. If not, see https://www.gnu.org/licenses/.

import SwiftUI

extension View {
    /// The `onLoad` modifier is kind of an SwiftUI's equivalent of `viewDidLoad` callback in UIKit.
    /// Under the hood it still relies on `onAppear` callback but it's called only once instead.
    public func onLoad(perform action: (() -> Void)? = nil) -> some View {
        modifier(ViewDidLoadModifier(action: action))
    }
}

private struct ViewDidLoadModifier: ViewModifier {
    @State private var viewDidLoad = false
    let action: (() -> Void)?

    func body(content: Content) -> some View {
        content
            .onAppear {
                if viewDidLoad == false {
                    viewDidLoad = true
                    action?()
                }
            }
    }
}