ios - 运行FetchRequest时出错(核心数据，SwiftUI)

Question

与SwiftUI一起使用Core Data时，我的以下代码编译没有问题:

@FetchRequest(
    entity: MyEntity.entity(),
    sortDescriptors: [NSSortDescriptor(keyPath: \MyEntity.name, ascending: true)]
) var myList: FetchedResults<MyEntity>

......

func wonderFunctio() {
    let theName = "Donald-Duck"
    print(#function)
    ......
    print("myList = \(myList.count)")
    
    let predic = NSPredicate(format: "name == %@", theName)
    if FetchRequest<NSFetchRequestResult>(entity: MyEntity.entity(),
                                          sortDescriptors: [],
                                          predicate: predic)
        .wrappedValue.count != 0 {
        print("Useful message ....")
    }

不幸的是，运行时出现问题。我在if FetchRequest行中收到此错误。

  Thread 1: EXC_BREAKPOINT (code=1, subcode=0x1eceee678)

我的代码中是否有任何看起来不合适的内容？

Answer 1

FetchRequest<NSFetchRequestResult>(entity...是一个属性包装器，因此我认为它是无效的用法。
这是直接使用CoreData NSFetchRequest的可能解决方案，这似乎是在函数中使用的更合适的方法

let theName = "Donald-Duck"
let request: NSFetchRequest<MyEntity> = MyEntity.fetchRequest()
request.predicate = NSPredicate(format: "name == %@", theName)

if let result = try? self.context.count(for: request), result != 0 {
    // .. do anything needed
}