Swift DynamicFetchView 获取限制

Question

我一直在处理一个提取请求，使用这里的答案似乎工作正常：

import CoreData
import SwiftUI

struct DynamicFetchView<T: NSManagedObject, Content: View>: View {
    let fetchRequest: FetchRequest<T>
    let content: (FetchedResults<T>) -> Content

    var body: some View {
        self.content(fetchRequest.wrappedValue)
    }

    init(predicate: NSPredicate?, fetchLimit:Int = 5, sortDescriptors: [NSSortDescriptor], @ViewBuilder content: @escaping (FetchedResults<T>) -> Content) {
        fetchRequest = FetchRequest<T>(entity: T.entity(), sortDescriptors: sortDescriptors, predicate: predicate, fetchLimit)
        self.content = content
    }

    init(fetchRequest: NSFetchRequest<T>, @ViewBuilder content: @escaping (FetchedResults<T>) -> Content) {
        self.fetchRequest = FetchRequest<T>(fetchRequest: fetchRequest)
        self.content = content
    }
}

在我看来：

DynamicFetchView(predicate: NSPredicate(format: "Brand CONTAINS %@", "GAP"), sortDescriptors: [NSSortDescriptor(keyPath: \store.brandName, ascending: false)]) { (clothing: FetchedResults<Store>) in
    HStack {
        Text("Number of Gap products: \(clothing.count)")
            .bold()
            .underline()
        List {
            ForEach(clothing) { Store in
                Text("Clothing Name: \(Store.clothingName!)")
            }
        }
    }

DynamicFetchView 可以很好地显示获取请求中的所有内容，但我想将其限制为 5。我尝试添加 fetchLimit=5 但这似乎没有任何区别。

Answer 1

解决方法如下：

struct DynamicFetchView<T: NSManagedObject, Content: View>: View {
    let fetchRequest: FetchRequest<T>
    let content: (FetchedResults<T>) -> Content

    var body: some View {
        self.content(fetchRequest.wrappedValue)
    }

    init(predicate: NSPredicate?, fetchLimit:Int = 5, sortDescriptors: [NSSortDescriptor], @ViewBuilder content: @escaping (FetchedResults<T>) -> Content) {
        guard let entityName = T.entity().name else { fatalError("Unknown entity") }

        let request = NSFetchRequest<T>(entityName: entityName)
        request.fetchLimit = fetchLimit
        request.sortDescriptors = sortDescriptors
        request.predicate = predicate

        self.init(fetchRequest: request, content: content)
    }

    init(fetchRequest: NSFetchRequest<T>, @ViewBuilder content: @escaping (FetchedResults<T>) -> Content) {
        self.fetchRequest = FetchRequest<T>(fetchRequest: fetchRequest)
        self.content = content
    }
}

Swift DynamicFetchView 获取限制

Swift DynamicFetchView fetchlimit

core-data

nsfetchrequest

swift

swiftui