mirror of
https://github.com/Instagram/IGListKit
synced 2026-05-18 14:58:34 +00:00
5f3c7e0319
Summary: This diff introduces two experimental APIs to make `IGListKit` more usable with Swift values types: - The `ListIdentifiable` protocol, which provides the equivalent of the diff identifier half of `ListDiffable`. For equality, we just use Swift's native `Equatable`. - The `ListValueSectionController` base class, which provides a section controller interface for use with `ListIdentifiable` values. These two APIs work together through the use of a private box class. I'd like to keep this detail hidden from callers, so that product code only deals with native Swift types. Differential Revision: D23606413 fbshipit-source-id: 23718c508643f165c74550f1515d77448bd42d42
38 lines
1.6 KiB
Swift
38 lines
1.6 KiB
Swift
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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import IGListKit
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/// A generic section controller that supports any Swift value conforming to `ListIdentifiable`.
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///
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/// For a type-safe base class for `ListDiffable` objects, see `ListGenericSectionController` instead.
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///
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/// `ListValueSectionController` is an experimental, under-development API, and may change without warning in the future.
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open class ListValueSectionController<Value: ListIdentifiable>: ListSectionController {
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/// The section controller's current value.
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///
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/// This value will be `nil` temporarily after initialization, but is exposed as an implicitly-unwrapped
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/// optional because it will be set by `didUpdate(to:)` before any other methods, like `cellForItem(at:)`,
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/// are invoked.
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public private(set) var value: Value!
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/// Subclasses of `ListValueSectionController` may not override `didUpdate(to:)` for objects.
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/// Instead, they must use the overload for generic values.
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public final override func didUpdate(to object: Any) {
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if let value = Value(diffable: object) {
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self.value = value
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didUpdate(to: value)
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} else {
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fatalError("Expected object for value section controller to be a boxed \(Value.self), but it was \(object)")
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}
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}
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/// Updates the section controller to a new value.
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///
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/// Subclasses of `ListValueSectionController` may override this method. Calling `super` is not required.
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open func didUpdate(to value: Value) {}
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}
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