Multi file uploads (#4358)

* Allow MediaPickerScreen users to select the media selection mode (single or multiple)

* Fix cancellation

* Add support for multiple media URLs on the MediaUploadPreviewScreen.

* Support processing more URLs on the `MediaUploadingPreprocessor` and sending more on the `MediaUploadPreviewScreen`

* Add feature flag for `multipleAttachmentUploadEnabled`

* Add a label showing the current preview item index in the MediaUploadPreviewScreen

* Add support for dragging and dropping or pasting multiple items at the same time.

* Support sharing more than one file through the share extension.

* Limit the number of items that can be shared in one go to 5.

* Fix unit tests

* Fix incorrect fatal error when dealing with single selection media pickers.

* Document the `multipleAttachmentUploadEnabled` usage in the context of the MediaPicker.

* Use a task group for processing selected media in the photo library picker.

* Use a task group for processing multiple selected media in the MediaUploadingPreprocessor

* Switch the maximum number of items that can be shared to 10.

* Allow multiple items to be pasted at the same time.

ElementX/Sources/Screens/RoomScreen/ComposerToolbar/ComposerToolbarModels.swift

@@ -27,7 +27,7 @@ enum ComposerToolbarViewModelAction {
     case editLastMessage
     case attach(ComposerAttachmentType)
 
-    case handlePasteOrDrop(provider: NSItemProvider)
+    case handlePasteOrDrop(providers: [NSItemProvider])
 
     case composerModeChanged(mode: ComposerMode)
     case composerFocusedChanged(isFocused: Bool)
@@ -46,7 +46,7 @@ enum ComposerToolbarViewAction {
     case cancelReply
     case cancelEdit
     case attach(ComposerAttachmentType)
-    case handlePasteOrDrop(provider: NSItemProvider)
+    case handlePasteOrDrop(providers: [NSItemProvider])
     case enableTextFormatting
     case composerAction(action: ComposerAction)
     case selectedSuggestion(_ suggestion: SuggestionItem)

ElementX/Sources/Screens/RoomScreen/ComposerToolbar/ComposerToolbarViewModel.swift

@@ -216,8 +216,8 @@ final class ComposerToolbarViewModel: ComposerToolbarViewModelType, ComposerTool
         case .attach(let attachment):
             state.bindings.composerFocused = false
             actionsSubject.send(.attach(attachment))
-        case .handlePasteOrDrop(let provider):
-            actionsSubject.send(.handlePasteOrDrop(provider: provider))
+        case .handlePasteOrDrop(let providers):
+            actionsSubject.send(.handlePasteOrDrop(providers: providers))
         case .enableTextFormatting:
             state.bindings.composerFormattingEnabled = true
             state.bindings.composerFocused = true

ElementX/Sources/Screens/RoomScreen/ComposerToolbar/View/ComposerToolbar.swift

@@ -181,8 +181,8 @@ struct ComposerToolbar: View {
             sendMessage()
         } editAction: {
             context.send(viewAction: .editLastMessage)
-        } pasteAction: { provider in
-            context.send(viewAction: .handlePasteOrDrop(provider: provider))
+        } pasteAction: { providers in
+            context.send(viewAction: .handlePasteOrDrop(providers: providers))
         } cancellationAction: {
             switch context.viewState.composerMode {
             case .edit:
@@ -259,7 +259,7 @@ struct ComposerToolbar: View {
                             viewModel: context.viewState.wysiwygViewModel,
                             itemProviderHelper: ItemProviderHelper(),
                             keyCommands: context.viewState.keyCommands) { provider in
-            context.send(viewAction: .handlePasteOrDrop(provider: provider))
+            context.send(viewAction: .handlePasteOrDrop(providers: [provider]))
         }
     }
     

ElementX/Sources/Screens/RoomScreen/ComposerToolbar/View/MessageComposer.swift

@@ -10,7 +10,7 @@ import SwiftUI
 import WysiwygComposer
 
 typealias GenericKeyHandler = (_ key: UIKeyboardHIDUsage) -> Void
-typealias PasteHandler = (NSItemProvider) -> Void
+typealias PasteHandler = ([NSItemProvider]) -> Void
 
 struct MessageComposer: View {
     @Binding var plainComposerText: NSAttributedString

ElementX/Sources/Screens/RoomScreen/ComposerToolbar/View/MessageComposerTextField.swift

@@ -190,8 +190,8 @@ private struct UITextViewWrapper: UIViewRepresentable {
             textView.insertText("\n")
         }
 
-        func textView(_ textView: UITextView, didReceivePasteWith provider: NSItemProvider) {
-            pasteHandler(provider)
+        func textView(_ textView: UITextView, didReceivePasteWith providers: [NSItemProvider]) {
+            pasteHandler(providers)
         }
         
         func textViewDidChangeSelection(_ textView: UITextView) {
@@ -207,7 +207,7 @@ private struct UITextViewWrapper: UIViewRepresentable {
 private protocol ElementTextViewDelegate: AnyObject {
     func textViewDidReceiveShiftEnterKeyPress(_ textView: UITextView)
     func textViewDidReceiveKeyPress(_ textView: UITextView, key: UIKeyboardHIDUsage)
-    func textView(_ textView: UITextView, didReceivePasteWith provider: NSItemProvider)
+    func textView(_ textView: UITextView, didReceivePasteWith providers: [NSItemProvider])
 }
 
 private class ElementTextView: UITextView, PillAttachmentViewProviderDelegate {
@@ -280,19 +280,19 @@ private class ElementTextView: UITextView, PillAttachmentViewProviderDelegate {
             return false
         }
 
-        return UIPasteboard.general.itemProviders.first?.isSupportedForPasteOrDrop ?? false
+        return UIPasteboard.general.itemProviders.filter { !$0.isSupportedForPasteOrDrop }.isEmpty
     }
 
     override func paste(_ sender: Any?) {
-        guard let provider = UIPasteboard.general.itemProviders.first,
-              provider.isSupportedForPasteOrDrop else {
-            // If the item is not supported for media upload then
-            // just try pasting its contents into the textfield
+        let providers = UIPasteboard.general.itemProviders
+        
+        // Use the default behavior if there are any unsupported providers
+        guard providers.filter({ !$0.isSupportedForPasteOrDrop }).isEmpty else {
             super.paste(sender)
             return
         }
-
-        elementDelegate?.textView(self, didReceivePasteWith: provider)
+        
+        elementDelegate?.textView(self, didReceivePasteWith: providers)
     }
     
     // MARK: PillAttachmentViewProviderDelegate