過濾境界與斯威夫特

Question

對象

我總是試圖使用NSPredicate篩選我的境界數據庫時出現以下錯誤。這是我已經試過：

let realm = try! Realm() 
let predicate = NSPredicate(format: "typez.text.filter = 'special'") 
let filterThis = realm.objects(Publication).filter(predicate) 
print(filterThis) 

我的模型類的相關部分是：

class Publication: Object, Mappable { 
    dynamic var id: Int = 0 
    var typez = List<getType>() 
    dynamic var url: String? 
} 

class getType: Object, Mappable { 
    dynamic var text: String = "" 
} 

Answer 1

我不經常使用NSPredicate的直接，而不是我做的過濾器中內嵌謂詞關閉參數中。

let realm = try! Realm() 
        //Array of publications    
    let realmObjects = realm.objects(Publication) 
    //any publication where .text property == special will be filtered. and filter out empty array 
    let filterThis = realmObjects.filter({ $0.getType.filter({ $0.text == "special" } != []) }) 
    print(filterThis) 

Answer 2

你提到的模型類的相關部分看起來像這樣：

class Publication: Object, Mappable { 
    dynamic var id: Int = 0 
    var typez = List<getType>() 
    dynamic var url: String? 
} 

class getType: Object, Mappable { 
    dynamic var text: String = "" 
} 

如果我理解正確的話，你想找到Publication實例是在其typez清單，text條目等於special。你可以表達爲：

let realm = try! Realm() 
let result = realm.objects(Publication).filter("ANY typez.text = 'special'") 
print(result) 

Answer 3

我不喜歡接受的答案在這裏，因爲它實際上並沒有回答這個問題......但後來它比我意識到幫助了我。我現在將盡可能使用閉包而不是NSPredicates。這個問題的實際答案應該是@ NSGangster的答案的一個稍微修改版本：

let realm = try! Realm() 
    //Array of publications    
    let realmObjects = realm.objects(Publication) 
    //any publication where .text property == special will be filtered. and filter out empty array 
    let filterThis = realmObjects.filter({ $0.typez.filter({ $0.text == "special" } != []) }) 
    print(filterThis) 

..或者與之相近的東西。

但我所尋找的是有點不同。我需要一種方法來過濾多字字符串的確切單詞，並且使用帶有「CONTAINS」的NSPredicate將匹配任何包含的子字符串，例如，搜索「紅色」會匹配「fred」。境界不支持「喜歡」或正則表達式還，所以使用封閉是我能得到工作的唯一的事：

//I was going for a "related terms" result for a dictionary app 
let theResults = terms.filter(
    { 
     //Looking for other terms in my collection that contained the 
     //title of the current term in their definition or more_info strings 
     $0.definition.components(separatedBy: " ").contains(term.title) || 
     $0.more_info.components(separatedBy: " ").contains(term.title) 
    } 
) 

儘可能多的一天，我花了搜索，希望這可以幫助別人帶一個類似的問題。