Advanced List View for SwiftUI with pagination & different states

by iOS Example

AdvancedList

This package provides a wrapper view around the SwiftUI List view which adds pagination (through my ListPagination package) and an empty, error and loading state including a corresponding view.


?
Installation

Add this Swift package in Xcode using its Github repository url. (File > Swift Packages > Add Package Dependency…)


?
How to use

The AdvancedList view is similar to the List and ForEach views. You have to pass data (RandomAccessCollection) and a view provider ((Data.Element) -> some View) to the initializer. In addition to the List view the AdvancedList expects a list state and corresponding views. Modify your data anytime or hide an item through the content block if you like. The view is updated automatically
?
.

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    Text(error.localizedDescription)
        .lineLimit(nil)
}, loadingStateView: {
    Text("Loading ...")
})


?
Custom List view

Starting from version 6.0.0 you can use a custom list view instead of the SwiftUI List used under the hood. As an example you can now easily use the LazyVStack introduced in iOS 14 if needed.

Upgrade from version 5.0.0 without breaking anything. Simply add the listView parameter after the upgrade:

AdvancedList(yourData, listView: { rows in
    if #available(iOS 14, macOS 11, *) {
        ScrollView {
            LazyVStack(alignment: .leading, content: rows)
                .padding()
        }
    } else {
        List(content: rows)
    }
}, content: { item in
    Text("Item")
}, listState: listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    Text(error.localizedDescription)
        .lineLimit(nil)
}, loadingStateView: {
    Text("Loading ...")
})


?
Pagination

The Pagination functionality is now (>= 5.0.0) implemented as a modifier. It has three different states: error, idle and loading. If the state of the Pagination changes the AdvancedList displays the view created by the view builder of the specified pagination object (AdvancedListPagination). Keep track of the current pagination state by creating a local state variable (@State) of type AdvancedListPaginationState. Use this state variable in the content ViewBuilder of your pagination configuration object to determine which view should be displayed in the list (see the example below).

If you want to use pagination you can choose between the lastItemPagination and the thresholdItemPagination. Both concepts are described here. Just specify the type of the pagination when adding the .pagination modifier to your AdvancedList.

The view created by the content ViewBuilder of your pagination configuration object will only be visible below the List if the last item of the List appeared! That way the user is only interrupted if needed.

Example:

@State private var paginationState: AdvancedListPaginationState = .idle

AdvancedList(...)
.pagination(.init(type: .lastItem, shouldLoadNextPage: {
    paginationState = .loading
    DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
        items.append(contentsOf: moreItems)
        paginationState = .idle
    }
}) {
    switch paginationState {
    case .idle:
        EmptyView()
    case .loading:
        if #available(iOS 14.0, *) {
            ProgressView()
        } else {
            Text("Loading ...")
        }
    case let .error(error):
        Text(error.localizedDescription)
    }
})


?
Move and
?️
delete items

To enable the move or delete function just use the related onMove or onDelete view modifier. Per default the functions are disabled if you don’t add the view modifiers.

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    Text(error.localizedDescription)
        .lineLimit(nil)
}, loadingStateView: {
    Text("Loading ...")
})
.onMove { (indexSet, index) in
    // move me
}
.onDelete { indexSet in
    // delete me
}


?️
Filtering

You can hide items in your list through the content block. Only return a view in the content block if a specific condition is met.


?
Example

The following code shows how easy-to-use the view is:

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
})

For more examples take a look at AdvancedList-SwiftUI.

Migration

Migration 2.x -> 3.0

The AdvancedList was dramatically simplified and is now more like the List and ForEach SwiftUI views.

  1. Delete your list service instances and directly pass your data to the list initializer
  2. Create your views through a content block (initializer parameter) instead of conforming your items to View directly (removed type erased wrapper AnyListItem)
  3. Pass a list state binding to the initializer (before: the ListService managed the list state)
  4. Move and delete: Instead of setting AdvancedListActions on your list service just pass a onMoveAction and/or onDeleteAction block to the initializer

Before:

import AdvancedList

let listService = ListService()
listService.supportedListActions = .moveAndDelete(onMove: { (indexSet, index) in
    // please move me
}, onDelete: { indexSet in
    // please delete me
})
listService.listState = .loading

AdvancedList(listService: listService, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
}, pagination: .noPagination)

listService.listState = .loading
// fetch your items ...
listService.appendItems(yourItems)
listService.listState = .items

After:

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: $listState, onMoveAction: { (indexSet, index) in
    // move me
}, onDeleteAction: { indexSet in
    // delete me
}, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
}, pagination: .noPagination)
Migration 3.0 -> 4.0

Thanks to a hint from @SpectralDragon I could refactor the onMove and onDelete functionality to view modifiers.

Before:

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: $listState, onMoveAction: { (indexSet, index) in
    // move me
}, onDeleteAction: { indexSet in
    // delete me
}, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
}, pagination: .noPagination)

After:

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: $listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
}, pagination: .noPagination)
.onMove { (indexSet, index) in
    // move me
}
.onDelete { indexSet in
    // delete me
}
Migration 4.0 -> 5.0

Pagination is now implemented as a modifier
?
And last but not least the code documentation arrived
?

Before:

<div class="highlight highlight-source-swift position-relative" data-snippet-clipboard-copy-content="private lazy var pagination: AdvancedListPagination = {
.thresholdItemPagination(errorView: { error in
AnyView(
VStack {
Text(error.localizedDescription)
.lineLimit(nil)
.multilineTextAlignment(.center)

Button(action: {
// load current page again
}) {
Text("Retry")
}.padding()
}
)
}, loadingView: {
AnyView(
VStack {
Divider()
Text("Loading…")
}
)
}, offset: 25, shouldLoadNextPage: {
// load next page
}, state: .idle)
}()

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
Text("Item")
}, listState: $listState, emptyStateView: {
Text("No data")
}, errorStateView: { error in
VStack {
Text(error.localizedDescription)
.lineLimit(nil)

Button(action: {
// do something
}) {
Text("Retry")
}
}
}, loadingStateView: {
Text("Loading …")
}, pagination: pagination)

“>

private lazy var pagination: AdvancedListPagination<AnyView, AnyView> = {
    .thresholdItemPagination(errorView: { error in
        AnyView(
            VStack {
                Text(error.localizedDescription)
                    .lineLimit(nil)
                    .multilineTextAlignment(.center)

                Button(action: {
                    // load current page again
                }) {
                    Text("Retry")
                }.padding()
            }
        )
    }, loadingView: {
        AnyView(
            VStack {
                Divider()
                Text("Loading...")
            }
        )
    }, offset: 25, shouldLoadNextPage: {
        // load next page
    }, state: .idle)
}()

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: $listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
}, pagination: pagination)

After:

@State private var listState: ListState = .items
@State private var paginationState: AdvancedListPaginationState = .idle

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: $listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
})
.pagination(.init(type: .lastItem, shouldLoadNextPage: {
    paginationState = .loading
    DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
        items.append(contentsOf: moreItems)
        paginationState = .idle
    }
}) {
    switch paginationState {
    case .idle:
        EmptyView()
    case .loading:
        if #available(iOS 14.0, *) {
            ProgressView()
        } else {
            Text("Loading ...")
        }
    case let .error(error):
        Text(error.localizedDescription)
    }
})
Migration 6.0 -> 7.0

I replaced the unnecessary listState Binding and replaced it with a simple value parameter.

Before:

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: $listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
}, pagination: .noPagination)

After:

import AdvancedList

@State private var listState: ListState = .items

AdvancedList(yourData, content: { item in
    Text("Item")
}, listState: listState, emptyStateView: {
    Text("No data")
}, errorStateView: { error in
    VStack {
        Text(error.localizedDescription)
            .lineLimit(nil)
        
        Button(action: {
            // do something
        }) {
            Text("Retry")
        }
    }
}, loadingStateView: {
    Text("Loading ...")
}, pagination: .noPagination)

GitHub

https://github.com/crelies/AdvancedList