SwiftData报错：Composite Coder仅支持Keyed Container，ModelContainer初始化失败

实例化ModelContainer对象时触发错误：Thread 1: Fatal error: Composite Coder only supports Keyed Container。自定义模型SingleFolder，想要生成可全局访问的ModelContainer单例，使用Xcode 15.0 beta4、iOS 17.0模拟器，相关代码如下：

DatabaseService 代码 #

class DatabaseService {
    static var shared = DatabaseService()
    
    var container: ModelContainer?
    var context: ModelContext?
    
    init() {
        do {
            container = try ModelContainer(for: [SingleFolder.self])
            if let container {
                context = ModelContext(container)
            }
        } catch {
            print(error)
        }
    }
}

SingleFolder 模型代码 #

@Model class SingleFolder {
    let creationTime: Date
    var editTime: Date
    var folderName: String
    
    var frame: CGRect = CGRect.zero

    init(creationTime: Date, editTime: Date, folderName: String) {
        self.creationTime = creationTime
        self.editTime = editTime
        self.folderName = folderName
    }
}

• 核心问题：SwiftData在iOS 17/Xcode 15 beta阶段暂不原生支持CGRect这类复杂值类型，其内置编码器无法处理非基础类型的编码逻辑，导致初始化ModelContainer时抛出编码错误。
• 解决步骤：
  1. 直接移除SingleFolder中的frame: CGRect属性，或者将其拆分为SwiftData支持的基础数值类型（比如frameX、frameY、frameWidth、frameHeight四个Double类型属性）。
  2. 若需保留CGRect的使用体验，可通过计算属性封装基础值的转换，示例代码：

     @Model class SingleFolder {
         let creationTime: Date
         var editTime: Date
         var folderName: String
         
         // 用SwiftData支持的基础类型存储CGRect参数
         var frameX: Double = 0.0
         var frameY: Double = 0.0
         var frameWidth: Double = 0.0
         var frameHeight: Double = 0.0
         
         // 对外暴露CGRect类型的计算属性
         var frame: CGRect {
             get {
                 CGRect(x: frameX, y: frameY, width: frameWidth, height: frameHeight)
             }
             set {
                 frameX = newValue.origin.x
                 frameY = newValue.origin.y
                 frameWidth = newValue.size.width
                 frameHeight = newValue.size.height
             }
         }
     
         init(creationTime: Date, editTime: Date, folderName: String) {
             self.creationTime = creationTime
             self.editTime = editTime
             self.folderName = folderName
         }
     }
     

  3. 修改后重新初始化ModelContainer，编码错误即可消除。

内容的提问来源于stack exchange，提问作者ikunhub