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https://github.com/octree/LegoKit


https://github.com/octree/LegoKit

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README

        

# LegoKit

使用声明式语法组织 UICollectionView。支持类似 SwiftUI 的 `@State`、`@Published` 和 `@StateObject`

## Installation

### Swift Package Manager

File > Swift Packages > Add Package Dependency
Add https://github.com/octree/LegoKit.git
Select "Up to Next Major" with "1.0.0"

## How to Use

### Cell 的实现

```swift
public struct ColorItem: TypedItemType {
public typealias CellType = ColorCell
public var id: UUID
public var color: UIColor
public var height: CGFloat
}

public class ColorCell: UICollectionViewCell, TypedCellType {
public typealias Item = ColorItem

public func update(with item: ColorItem) {
backgroundColor = item.color
}
}
```

* id: 可以是任意 `Hashable`类型,为了给以后做动画,进行 diff 准备的预留属性。
* 其他的属性,是用来配置 Cell 的信息
* Cell 需要实现 `TypedCellType` 的方法
* **update**:根据对应的 `Item` 更新 UI

### 渲染 UICollectionView

#### 配置 Lego

```swift
class ViewController: UIViewController {
var lego: Lego {
Lego {
Section(id: ..., WaterfallLayout()) {
ColorItem(...)
ColorItem(...)
ColorItem(...)
}

Section(WaterfallLayout()) {
for elt in array {
ColorItem(elt)
}
}
}
}
}
```

* Lego 用于描述 **CollectionView** 中的 Section 和 Cell 的信息
* 使用类似 SwiftUI 的声明式语法构建
* 支持 `if`、`#if @available `、`for in`、`switch case`等结构

#### 渲染

```swift
class ViewController: UIViewController {
lazy var legoRenderer: LegoRenderer = .init(lego: lego)
override func viewDidLoad() {
legoRenderer.render(in: view) {
$0.backgroundColor = UIColor(white: 0.95, alpha: 1)
}
}

private func reload() {
legoRenderer.apply(lego)
}
}
```

### 使用 @State、@StateObject 等,自动更新 CollectionView

```swift
class ViewModel: LegoObservableObject {
@LegoPublished var items: [ColorItem] = []
func addRandomColor() {
items.append(.random)
}
}

class ViewController: UIViewController, LegoContainer {
@StateObject var viewModel = ViewModel()
@State var flag: Bool = false
lazy var legoRenderer: LegoRenderer = .init(lego: lego)
var lego: Lego {
Lego {
Section(id: 0, layout: WaterfallLayout()) {
if flag {
// ... some items.
}
viewModel.items
}
}
}

override func viewDidLoad() {
super.viewDidLoad()
legoRenderer.render(in: view) {
$0.backgroundColor = UIColor(white: 0.95, alpha: 1)
}
}
}
```

* 当用于配置 Lego 的数据,使用了 `@State` 或者 `@StateObject ` 时就不需要手动调用 `apply` 函数。当数据发生变动时,会自动更新 `UICollectionView`。

## License

**LegoKit** is available under the MIT license. See the LICENSE file for more info.