使用 swift 在 xcode 6 中自定义 NSValueTransformer
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Custom NSValueTransformer in xcode 6 with swift
提问by marschro
Did anyone successfully implement a custom NSValueTransformer in xcode 6 beta with swift?
有没有人在 xcode 6 beta 中使用 swift 成功实现自定义 NSValueTransformer？
I have the following swift class:
我有以下快速课程：
import Foundation
class myTransformer: NSValueTransformer {
let amount = 100
override class func transformedValueClass() -> AnyClass!
{
return NSNumber.self
}
override func transformedValue(value: AnyObject!) -> AnyObject! {
return value.integerValue + amount
}
}
So all this transformer should do is, adding 100 to a given value in the gui.
所以这个转换器应该做的就是将 100 添加到 gui 中的给定值。
As you can see, the transformer class appears now in the Value Transformer drop down in IB.
如您所见，转换器类现在出现在 IB 的 Value Transformer 下拉列表中。
But if I choose this transformer the application crashes with:
但是如果我选择这个变压器，应用程序就会崩溃：
2014-08-27 20:12:17.686 cdTest[44134:303]
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException',
reason: 'Cannot find value transformer with name newTransformer'
Is it right to register this transformer in the AppDelegate with
在 AppDelegate 中注册这个转换器是否正确
override class func initialize() {
let newTransformer = myTransformer()
}
Does anyone know how this whole stuff should work?
有谁知道这整个东西应该如何工作？
kind regards! martin
亲切的问候！马丁
采纳答案by 042e
After you initialise newTransformeryou should also include the line:
初始化newTransformer后，您还应该包含以下行：
NSValueTransformer.setValueTransformer(newTransformer, forName: "myTransformer")
Then in your Interface Builder you should use myTransformerinstead of newTransformerunder the Value Transformer dropdown.
然后在您的界面生成器中，您应该在 Value Transformer 下拉列表下使用myTransformer而不是newTransformer。
回答by user500
From Xcode release notes:
来自 Xcode 发行说明：
If you set a Swift subclass of NSValueTransformer as a binding's value transformer, the XIB or storyboard will contain an invalid reference to the class, and the binding will not work properly at runtime. You can either enter a mangled class name into the Value Transformer field or add the @objc(…) attribute to the NSValueTransformer subclass to solve this problem. (17495784)
如果您将 NSValueTransformer 的 Swift 子类设置为绑定的值转换器，则 XIB 或故事板将包含对该类的无效引用，并且该绑定在运行时将无法正常工作。您可以在 Value Transformer 字段中输入经过修改的类名，也可以将 @objc(...) 属性添加到 NSValueTransformer 子类来解决此问题。(17495784)
From Swift guide:
来自 Swift 指南：
To make your Swift class accessible and usable back in Objective-C, make it a descendant of an Objective-C class or mark it with the @objc attribute. To specify a particular name for the class to use in Objective-C, mark it with @objc(<#name#>), where <#name#> is the name that your Objective-C code will use to reference the Swift class. For more information on @objc, see Swift Type Compatibility.
要使您的 Swift 类在 Objective-C 中可访问和可用，请使其成为 Objective-C 类的后代或使用 @objc 属性标记它。要为在 Objective-C 中使用的类指定一个特定的名称，用@objc(<#name#>) 标记它，其中 <#name#> 是你的 Objective-C 代码将用来引用 Swift 类的名称. 有关 @objc 的更多信息，请参阅 Swift 类型兼容性。
Solution:
解决方案：
Declare your class as @objc(myTransformer) class myTransformer: NSValueTransformerand then you can use "myTransformer" as name...
将您的课程声明为@objc(myTransformer) class myTransformer: NSValueTransformer，然后您可以使用“myTransformer”作为名称...
