在Realm中查询（使用Swift）

问题描述

限时删除！！

我正在玩realm.io。我写了几个对象，现在我想查询它们。我的数据类：

I'm toying with realm.io. I've written a couple of objects, and now I want to query for them. My data class:

class Sample : RLMObject {
    dynamic var sampleKey : String = ""
}

和我的查询代码

@IBAction func readLocalRecord(sender: UIButton) {

    let s : NSString = NSString.stringWithString("sampleKey == SampleValue")
    let p : NSPredicate = NSPredicate(format: "sampleKey = %@", argumentArray: NSArray(object: NSString.stringWithString("SampleValue")))

    // the following throws exception, that I cannot catch in Swift:
    //   'Unsupported predicate value type', reason: 'Object type any not supported'
    let r = Sample.objectsWithPredicate(p)
}

网站和RLMObject的标题表示我应该可以说Sample.objectsWhere（sampleKey ='SampleValue'）（或类似的） ），但objectsWhere给出一个编译错误抱怨函数不存在，并且没有autocomp拿它来。所以我尝试使用objectsForPredicate，但是这表示类型为'any'（通过标题挖掘，我发现这等于ObmC在Realm术语中的'id'类型）。我在这做错了什么？我试着显得非常明确，确保使用NSString而不是String和NSArray而不是Array，但仍然有些东西被解释为'id'而不是特定类型。

The webside, and the header of RLMObject, indicate that I should be able to say Sample.objectsWhere("sampleKey = 'SampleValue'") (or similar), but objectsWhere gives a compile error complaining the function isn't there, and there's no autocomplete for it. So I tried with objectsForPredicate instead, but this says that the type 'any' (digging through the headers, I find that this equals ObjC's 'id' type in Realm lingo). What am I doing wrong here? I try to be veery explicit, being sure to use NSString instead of String and NSArray instead of Array, but still something is interpreted as 'id' instead of a spesific type.

有什么建议吗？

干杯

-Nik

推荐答案

您的代码适用于Xcode 6 beta 5.顺便提一下，您不需要显式使用 NSArray 和 NSString 此处 - Swift将为您桥接到objective-c类型。以下适用于我并打印出我期望看到的对象：

Your code works fine for me with Xcode 6 beta 5. Incidentally, you don't need to explicitly use NSArray and NSString here - Swift will bridge to objective-c types for you. The following works for me and prints out the object I'd expect to see:

import Realm

class Sample : RLMObject {
    dynamic var sampleKey : String = ""
}

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func readLocalRecord() {

        // create some sample records
        RLMRealm.defaultRealm().beginWriteTransaction()
        var s = Sample()
        s.sampleKey = "Testing"
        RLMRealm.defaultRealm().addObject(s)
        var s2 = Sample()
        s2.sampleKey = "SampleValue"
        RLMRealm.defaultRealm().addObject(s2)
        RLMRealm.defaultRealm().commitWriteTransaction()

        let p : NSPredicate = NSPredicate(format: "sampleKey = %@", argumentArray: [ "SampleValue" ])

        let r = Sample.objectsWithPredicate(p)
        println(r)
    }

    func application(application: UIApplication!, didFinishLaunchingWithOptions launchOptions: NSDictionary!) -> Bool {

        readLocalRecord()

        return true
    }
}

输出为：

RLMArray <0x7fe8241218c0> (
    [0] Sample {
        sampleKey = SampleValue;
    }
}

请注意，Realm的 objectsWithPredicate 方法会返回一个Realm数组，而不是普通数组。

Note that Realm's objectsWithPredicate method returns you a Realm array, not a normal Array.

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