我使用Realm数据库在
swift中做新闻应用程序.在我的数据库中有相同的新闻类别.如何从Realm数据库中获取独特的价值？
我用主键
我用主键
class News: Object {
dynamic var newsID: String = ""
dynamic var newsTitle: String = ""
dynamic var newsFullText: String = ""
dynamic var newsImage: String = ""
dynamic var newsAutor: String = ""
dynamic var newsCommentCount: String = ""
dynamic var newsSeenCount: String = ""
dynamic var newsDate: String = ""
dynamic var newsCategory: String = ""
override static func primaryKey() -> String? {
return "newsID"
}
}
我试着去
let realm = try! Realm()
let menuName = realm.objects(News)
for i in menuName.filter("newsCategory") {
nameLabel.text = i.newsCategory
}
但这不起作用.
从Realm 3.10开始,现在可以
Add Results.distinct(by:) / -[RLMResults
distinctResultsUsingKeyPaths:],which return a Results containing only
objects with unique values at the given key paths.
旧的回应 – 在Realm 3.10之前
现在还不可能从Realm查询中获得“独特”的功能(跟踪未解决的问题here)
但是,我在上面提到的主题中提出了一些解决方法(请通过用户apocolipse阅读它以获得完整的上下文)：
// Query all users
let allUsers = Realm().objects(User)
// Map out the user types
let allTypes = map(allUsers) { $0.type }
// Fun part: start with empty array [],add in element to reduced array if its not already in,else add empty array
let distinctTypes = reduce(allTypes,[]) { $0 + (!contains($0,$1) ? [$1] : [] )
或者更好的是,使用Sets(通过用户jpsim)的不同方法：
let distinctTypes = Set(Realm().objects(User).valueForKey("type") as! [String])
