字典导致 swift/swiftui 出现奇怪的错误

Question

我有一本定义如下的字典

@State var instructorNamesDictionary: [String: [String]] = [:]

稍后将内容添加到 .task 中的字典中

    for course in courses{
         var updatedinstructors: [InstructorModel] = []
         for instructorID in course.instructors {
                let instructor = try await getInstructor(uid: instructorID)
                updatedinstructors.append(contentsOf: instructor)
                                    
                for names in updatedinstructors{
                                        
                  instructorNamesDictionary[instructorID] = [names.name]
                 }
           }                
                     
                                
 }

之后，我尝试将此字典使用到一个名为 CourseCard 的结构中，该结构接受一些参数：

struct CoursesCard: View {
    var name: String
    var image: Image
    var youtubeLinks: [String]
    var description: String
    var instructors: [String]
    var labels: [String]
    var isFree: Bool
    var ispro: Bool

//rest of design code

}

现在当我在另一个数组上执行 ForEach 循环时

ForEach(basicCourses){course in
  let image = images[course.image_ref] ?? Image("noImage")
                                   
CoursesCard(name: course.Name, image: image, youtubeLinks: course.youtube_videos, description: course.Description, instructors: instructorNamesDictionary[
     ForEach(course.instructors){instruc in
     instruc}] ?? ["No instructor"], labels: course.labels, isFree: course.isfree, ispro: isPro)

这给了我“无法将类型‘[CourseModel]’的值‘basicCourses’转换为预期类型‘Binding<[CourseModel]>’，请改用包装器”

但是，如果我传递另一个数组，则不会给出错误。

如果需要，这里是 CourseModel 和 InstructorModel：

struct CourseModel: Decodable,Identifiable {
    let id: String
    let Name: String
    let Description: String
    let image_ref: String
    let youtube_videos: [String]
    let labels: [String]
    let instructors: [String]
    let isfree: Bool
    enum CodingKeys: String, CodingKey {
        case id
        case Name
        case Description
        case image_ref
        case youtube_videos
        case labels
        case instructors
        case isfree
    }
    
}


struct InstructorModel: Decodable,Identifiable {
    let id: String
    let name: String
    
    enum CodingKeys: String, CodingKey {
        case id
        case name
    }
}

我尝试将 ForEach 循环更改为

ForEach($basicCourses){$course in
  let image = images[course.image_ref] ?? Image("noImage")
                                   
CoursesCard(name: course.Name, image: image, youtubeLinks: course.youtube_videos, description: course.Description, instructors: instructorNamesDictionary[
     ForEach(course.instructors){instruc in
     instruc}] ?? ["No instructor"], labels: course.labels, isFree: course.isfree, ispro: isPro)

但这只会抛出其他错误。

Answer 1

您应该在

CoursesCard

初始值设定项之外提取讲师姓名，并将它们作为字符串数组传递。

ForEach(basicCourses) { course in
    let image = images[course.image_ref] ?? Image("noImage")
    
    let instructorNames = course.instructors.compactMap { instructorID in
        instructorNamesDictionary[instructorID]?.first ?? "No Instructor"
    }
    
    CoursesCard(
        name: course.Name,
        image: image,
        youtubeLinks: course.youtube_videos,
        description: course.Description,
        instructors: instructorNames,
        labels: course.labels,
        isFree: course.isfree,
        ispro: isPro
    )
}