需要帮助过滤 Swift 中的核心数据 3

Question

我似乎无法在 Swift 3.

中找到与过滤核心数据相关的任何好的文档或教程

我有以下代码：

let tempVar: String = "abcdef"

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

do {

    /* Need code to modify the fetchRequest, so that it only pulls results where the "projectID" field is equal to whatever is stored in the tempVar variable. */

    cstProjectDetails = try context.fetch(CSTProjectDetails.fetchRequest())
} catch {
    print("There was an error fetching CST Project Details.")
}

基本上，我只是想在 fetchRequest 中添加一个简单的过滤器，以便它只从 "cstProjectDetails" 中提取结果，其中 "projectID" 字段等于先前设置的内容变量（在本例中，"tempVar"）。

有什么想法吗？

编辑：检查的答案对我有用，但我必须快速调整请求初始化程序的代码。这是我最终得到的代码：

do {
    let request: NSFetchRequest<CSTProjectDetails> = CSTProjectDetails.fetchRequest()
    request.predicate = NSPredicate(format: "projectID == %@", cstProjectID)
    cstProjectDetails = try context.fetch(request)
    print(cstProjectDetails)
} catch {
    print("There was an error fetching CST Project Details.")
}

Answer 1

您需要附加到请求的谓词：

let request = CSTProjectDetails.fetchRequest()
request.predicate = NSPredicate(format: "projectID == %@", tempVar)
cstProjectDetails = try context.fetch(request)

需要帮助过滤 Swift 中的核心数据 3

Need help filtering core data in Swift 3

filtering

core-data

nspredicate

swift3