ios RealmSwift：将结果转换为 Swift 数组
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RealmSwift: Convert Results to Swift Array
提问by Sahil Kapoor
What I want to implement:
我想要实现的：
class func getSomeObject() -> [SomeObject]? {
let objects = Realm().objects(SomeObject)
return objects.count > 0 ? objects : nil
}
How can I return object as [SomeObject]instead if Results?
我怎样才能返回对象，[SomeObject]而不是 if Results？
采纳答案by Sahil Kapoor
I found a solution. Created extension on Results.
我找到了解决方案。在结果上创建扩展。
extension Results {
func toArray<T>(ofType: T.Type) -> [T] {
var array = [T]()
for i in 0 ..< count {
if let result = self[i] as? T {
array.append(result)
}
}
return array
}
}
and using like
并使用像
class func getSomeObject() -> [SomeObject]? {
let objects = Realm().objects(SomeObject).toArray(SomeObject) as [SomeObject]
return objects.count > 0 ? objects : nil
}
回答by Mazyod
Weird, the answer is very straight forward. Here is how I do it:
奇怪，答案很直接。这是我如何做到的：
let array = Array(results) // la fin
回答by segiddins
If you absolutely must convert your Resultsto Array, keep in mind there's a performance and memory overhead, since Resultsis lazy. But you can do it in one line, as results.map { $0 }in swift 2.0 (or map(results) { $0 }in 1.2).
如果您绝对必须将您的 转换Results为Array，请记住有性能和内存开销，因为它Results是懒惰的。但是您可以在一行中完成，就像results.map { $0 }在 swift 2.0（或map(results) { $0 }1.2）中一样。
回答by NeverwinterMoon
With Swift 4.2 it's as simple as:
使用 Swift 4.2 就这么简单：
extension Results {
func toArray() -> [Element] {
return compactMap {
extension Results {
func toArray() -> [T] {
return self.map { extension Results {
func toArray<T>(type: T.Type) -> [T] {
return flatMap { extension Results {
func toArray<T>(type: T.Type) -> [T] {
return compactMap { extension Results {
func toArray<T>(ofType: T.Type) -> [T] {
var array = [T]()
for i in 0 ..< count {
if let result = self[i] as? T {
array.append(result)
}
}
return array
}
}
as? T }
}
}
as? T }
}
}
}
}
}
}
}
All the needed generics information is already a part of Resultswhich we extend.
所有需要的泛型信息已经是Results我们扩展的一部分。
回答by abdullahselek
This an another way of converting Resultsinto Array with an extension with Swift 3in a single line.
这是在一行中Results使用Swift 3扩展转换为 Array的另一种方式。
class func getSomeObject() -> [SomeObject]? {
let defaultRealm = try! Realm()
let objects = defaultRealm.objects(SomeObject.self).toArray(ofType : SomeObject.self) as [SomeObject]
return objects.count > 0 ? objects : nil
}
For Swift 4and Xcode 9.2
对于Swift 4和 Xcode 9.2
class func getSomeObject() -> [T]? {
let objects = Realm().objects(T.self as! Object.Type).toArray(ofType : T.self) as [T]
return objects.count > 0 ? objects : nil
}
With Xcode 10flatMapis deprecated you can use compactMapfor mapping.
随着Xcode的10flatMap已被弃用，你可以使用compactMap映射。
func toArray<T>(ofType: T.Type) -> [T] {
return flatMap { List(realm.objects(class))
as? T }
}
回答by Jaseem Abbas
Swift 3
斯威夫特 3
var refrenceBook:[RefrenceProtocol] = []
let faceTypes = Array(realm.objects(FaceType))
refrenceBook = faceTypes.map({extension Results {
var array: [Element]? {
return self.count > 0 ? self.map { Realm().objects(SomeClass.self).filter("someKey ENDSWITH %@", "sth").array
} : nil
}
}
as FaceType})
Usage
用法
extension Results {
func toArray<T>(ofType: T.Type) -> [T] {
let array = Array(self) as! [T]
return array
}
}
Alternative : Using generics
替代方法：使用泛型
let array = Realm().objects(SomeClass).toArray(ofType: SomeClass.self)
回答by Nosov Pavel
it's not a good idea to convert Results to Array, because Results is lazy. But if you need try this:
将结果转换为数组不是一个好主意，因为结果是惰性的。但如果你需要试试这个：
class func getSomeObject() -> [SomeObject]? {
var someObjects: [SomeObject] = []
let objects = Realm().objects(SomeObject)
for object in objects{
someObjects += [object]
}
return objects.count > 0 ? someObjects : nil
}
but better way is to pass Results wherever you need. Also you can convert Results to List instead of Array.
但更好的方法是在您需要的任何地方传递结果。您也可以将结果转换为列表而不是数组。
##代码##if the first func is not working you can try this one:
如果第一个 func 不起作用，您可以尝试这个：
##代码##回答by lindaaak
So, you can use like:
所以，你可以使用像：
##代码##回答by Vinayak
Solution for Swift 4, Realm 3
Swift 4, Realm 3 的解决方案
##代码##Now converting can be done as below
现在转换可以如下完成
##代码##回答by nRewik
I'm not sure, if there is any efficient way to do this.
我不确定，是否有任何有效的方法来做到这一点。
But you can do it by create a Swift array and append it in the loop.
但是您可以通过创建一个 Swift 数组并将其附加到循环中来实现。
##代码##If you feel it's too slow. I recommend you to pass around Realm Resultsobject directly.
如果你觉得它太慢了。我建议你Results直接传递 Realm对象。
