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@IBOutlet weak var myLabel: UILabel! var mymodel: Mymodel
由于我们的模型是在Objective-C中开发的,Mymodel看起来像这样:
@interface Mymodel : NsmanagedObject @property (nonatomic,retain) NSnumber * value; @end
因此,我想做这样的事情:
@H_708_21@myLabel.text <~ myProperty.rac_signalForSELEctor("value") |> map { (value: NSnumber) in return "\(value.IntegerValue + 1)" }
但是,这显然不起作用.我该如何处理这个问题? KVO如何通常用正常的模型属性实现?
我已经找到了关于这个主题的similar post.接受的答案建议使用viewmodels.但是,我不想用viewmodels替换现有的NsmanagedObject模型,而是希望保留我的模型,因为我喜欢通过XCode管理它们并通过CoreData存储它们.或者这对viewmodels来说是否可行?我错过了什么关键吗?
/// Send changes in the property value of a source object to another property on a target object,/// optionally using a mapping function to convert values as necessary. func bind<S,T>(propertyWithKey targetKey: String,on target: NSObject,toPropertyWithKey sourceKey: String,on source:NSObject,usingValueConversion source@R_965_10586@rgetValueConversion: ((S) -> T)? ) { var (source_signal,source_sink) = Signal<T,NSError>.pipe() var sourceSignalProducer = RACObserve(source,sourceKey).toSignalProducer() |> start(next: {value in if (value != nil) { if (source@R_965_10586@rgetValueConversion == nil) { sendNext(source_sink,value as! T) } else { let mappedValue = source@R_965_10586@rgetValueConversion!(value as! S) sendNext(source_sink,mappedvalue) } } }) var convertedValueRACSignal = tOracSignal( source_signal |> map {(value: T) in value as! AnyObject} ) convertedValueRACSignal ~> RAC(target,targetKey) } /// Send changes in the property value of a source object to another property on a target object. /// No conversion of values or value types is performed between source and target. func bind(propertyWithKey targetKey: String,on source:NSObject) { var (source_signal,source_sink) = Signal<AnyObject,sourceKey).toSignalProducer() |> start(next: {value in if (value != nil) { sendNext(source_sink,value!) } }) var convertedValueRACSignal = tOracSignal(source_signal) convertedValueRACSignal ~> RAC(target,targetKey) } // From Colin Eberhardt's post at http://blog.scottlogic.com/2014/07/24/mvvm-reactivecocoa-swift.html // a struct that replaces the RAC macro struct RAC { var target : NSObject! var keyPath : String! var nilValue : AnyObject! init(_ target: NSObject!,_ keyPath: String,nilValue: AnyObject? = nil) { self.target = target self.keyPath = keyPath self.nilValue = nilValue } func assignSignal(signal : RACSignal) { signal.setKeyPath(self.keyPath,onObject: self.target,nilValue: self.nilvalue) } } // From Colin Eberhardt's post at http://blog.scottlogic.com/2014/07/24/mvvm-reactivecocoa-swift.html infix operator ~> {} func ~> (signal: RACSignal,rac: RAC) { rac.assignSignal(signal) } // From Colin Eberhardt's post at http://blog.scottlogic.com/2014/07/24/mvvm-reactivecocoa-swift.html func RACObserve(target: NSObject!,keyPath: String) -> RACSignal { return target.rac_valuesForKeyPath(keyPath,observer: target) }
在你的例子中你称之为:
bind(propertyWithKey: "text",on: myTextField,toPropertyWithKey: "value",on: myProperty) { (number: NSnumber) in return "\(number.Integervalue)" as NSString }
我对ReactiveCocoa有些新意,所以上面的内容可能是一个天真的实现,但它可能会指向正确的方向.
更新
这种使用通道绑定的实现更紧凑,并利用RAC内置的KVO支持:
func bind<S,usingValueConversion source@R_965_10586@rgetValueConversion: ((S) -> T)? ) { var kvoChAnnelsource = RACKVOChAnnel(target: source,keyPath: sourceKey,nilValue: nil) var sourceSignalWithoutNils = kvoChAnnelsource.followingTerminal .filter { (var value:AnyObject?) -> Bool in return (value != nil) } var mappedsourceSignal = sourceSignalWithoutNils if (source@R_965_10586@rgetValueConversion != nil) { mappedsourceSignal = sourceSignalWithoutNils.map { (var s: AnyObject!) -> AnyObject! in var result : T = source@R_965_10586@rgetValueConversion!(s as! S) return result as! AnyObject } } var kvoChAnnelTarget = RACKVOChAnnel(target: target,keyPath: targetKey,nilValue: nil) mappedsourceSignal.subscribe(kvoChAnnelTarget.followingTerminal) }
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