使用 NSPredicate 过滤/取消过滤 SectionedFetchRequest 中的部分

Question

我正在使用 SectionedFetchRequest 对我的数据进行排序并提取到部分中。我构建了一个过滤器按钮，它应该过滤优先级为 0 的所有数据（它被保存为 int32 并更新 list.

阅读 Apple's Predicate Format Syntax 后，我尝试了以下方法：

sections.nsPredicate = NSPredicate(format: "priorityText CONTAINS[c] %@", "Today")
sections.nsPredicate = NSPredicate(format: "priority == %@", 0) //**
sections.nsPredicate = NSPredicate(format: "priority like %@", 0)
sections.nsPredicate = NSPredicate(format: "priorityText == %@", "Today")
sections.nsPredicate = NSPredicate(format: "priorityText like %@", "Today")
sections.nsPredicate = NSPredicate(format: "priority == %@", 0 as NSInteger) //**
sections.nsPredicate = NSPredicate(format: "priority == %@", 0 as Int32) //**

评论//**的没有崩溃，全部过滤掉了

我去 SO（比如 this one) and other sources (and this and this about predicateWithFortmat）阅读了一些问题，试图找出如何过滤掉整数。但我尝试的任何一个都不起作用。

此外，我不知道如何取消过滤数据...

实体

我的代码：

extension Task {
    @objc
    var priorityText: String{
        var result = ""
        switch self.priority {
        case 0: result = "Today"
        case 1: result = "Important Tasks"
        default: result = "All Others"
        }
        return result
    }
}


struct ContentView: View {
    @Environment(\.managedObjectContext) private var viewContext

    @SectionedFetchRequest(entity: Task.entity(),
                           sectionIdentifier: \.priorityText,
                           sortDescriptors: [NSSortDescriptor(keyPath: \Task.priority, ascending: true)],
                           predicate: nil,
                           animation: Animation.linear)
    var sections: SectionedFetchResults<String, Task>
    
    @State var filtered = false
    
    var body: some View {
        NavigationView {
            List {
                ForEach(sections) { section in
                    Section(header: Text(section.id.capitalized).fontWeight(.bold).foregroundColor(.primary)) {
                        ForEach(section) { task in
                            Text("\(task.tasktext!)")
                        }
                    }
                }
            }
            .toolbar {
                ToolbarItem(placement: .bottomBar) {
                    Button(action: {
                        filtered.toggle()
                        if filtered {
                            // check https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Predicates/Articles/pSyntax.html
                            //sections.nsPredicate = NSPredicate(format: "priorityText CONTAINS[c] %@", "Today")
                            //sections.nsPredicate = NSPredicate(format: "priority == %@", 0)
                            //sections.nsPredicate = NSPredicate(format: "priority like %@", 0)
                            //sections.nsPredicate = NSPredicate(format: "priorityText == %@", "Today")
                            //sections.nsPredicate = NSPredicate(format: "priorityText like %@", "Today")
                            sections.nsPredicate = NSPredicate(format: "priority == %@", 0 as NSInteger)
                        } else {
                           print("unfilter?")
                        }
                    }) {
                        Label("Filter", systemImage: filtered ? "line.3.horizontal.decrease.circle.fill": "line.3.horizontal.decrease.circle").foregroundColor(.primary)
                    }
                }
            }
            .listStyle(.plain)
        }
    }
}

编辑：

第一个问题（如何根据整数筛选数据）的答案是：

sections.nsPredicate = NSPredicate(format: "priority == %i",0)

并显示未过滤的数据：

sections.nsPredicate = NSPredicate(format: "priority >= %i",0)

Answer 1

我要回答我自己的问题：

要筛选：

sections.nsPredicate = NSPredicate(format: "priority == %i",0)

取消过滤：

sections.nsPredicate = NSPredicate(format: "priority >= %i",0)

使用 NSPredicate 过滤/取消过滤 SectionedFetchRequest 中的部分

Using NSPredicate to filter / unfilter sections in a SectionedFetchRequest

ios

swift

swiftui