104 lines
3.3 KiB
Swift
104 lines
3.3 KiB
Swift
//
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// Copyright 2021 New Vector Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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import Foundation
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import UIKit
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/// A `UserIndicator` represents the state of a temporary visual indicator, such as loading spinner, success notification or an error message. It does not directly manage the UI, instead it delegates to a `presenter`
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/// whenever the UI should be shown or hidden.
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///
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/// More than one `UserIndicator` may be requested by the system at the same time (e.g. global syncing vs local refresh),
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/// and the `UserIndicatorQueue` will ensure that only one indicator is shown at a given time, putting the other in a pending queue.
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///
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/// A client that requests an indicator can specify a default timeout after which the indicator is dismissed, or it has to be manually
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/// responsible for dismissing it via `cancel` method, or by deallocating itself.
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public class UserIndicator {
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public enum State {
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case pending
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case executing
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case completed
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}
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private let request: UserIndicatorRequest
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private let completion: () -> Void
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public private(set) var state: State
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public init(request: UserIndicatorRequest, completion: @escaping () -> Void) {
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self.request = request
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self.completion = completion
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state = .pending
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}
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deinit {
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complete()
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}
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internal func start() {
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guard state == .pending else {
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return
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}
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state = .executing
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request.presenter.present()
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switch request.dismissal {
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case .manual:
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break
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case .timeout(let interval):
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Timer.scheduledTimer(withTimeInterval: interval, repeats: false) { [weak self] _ in
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self?.complete()
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}
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}
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}
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/// Cancel the indicator, triggering any dismissal action / animation
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///
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/// Note: clients can call this method directly, if they have access to the `UserIndicator`. Alternatively
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/// deallocating the `UserIndicator` will call `cancel` automatically.
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/// Once cancelled, `UserIndicatorQueue` will automatically start the next `UserIndicator` in the queue.
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public func cancel() {
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complete()
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}
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private func complete() {
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guard state != .completed else {
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return
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}
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if state == .executing {
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request.presenter.dismiss()
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}
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state = .completed
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completion()
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}
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}
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public extension UserIndicator {
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func store<C>(in collection: inout C) where C: RangeReplaceableCollection, C.Element == UserIndicator {
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collection.append(self)
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}
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}
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public extension Collection where Element == UserIndicator {
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func cancelAll() {
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forEach {
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$0.cancel()
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}
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}
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}
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