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问题描述

我正在使用Alamofire,我使用枚举来描述我在自述文件中建议使用的API。



端点表示如下: p>

  public enum API {
case GetStops(stopCode:String?)
case GetPhysicalStops
case GetLinesColors
case GetNextDepartures(stopCode:String,departureCode:String?,linesCode:String?,destinationCode:String?)
}

可选参数是互斥的:

  public var URLRequest:NSMutableURLRequest {

let result((path:String,参数:[String:AnyObject]?)= {
switch self {
case .GetStops(let stopCode)where stopCode!= nil:
return(GetStops.json,[stopCode:stopCode!])
case .GetStops(_):
return(GetStops.json,nil)
case。 GetPhysicalStops:
返回(GetPhysicalStops.json,nil)
case .GetLinesColors:
return(GetLinesColors,nil)
case .GetNextDepartures(let stopCode,let departCode,_,_)where departureCode! = nil:
return(GetNextDepartures,[stopCode:stopCode,departureCode:departureCode!])
case .GetNextDepartures(let stopCode,_,let linesCode,_)where linesCode!= nil:
return(GetNextDepartures,[stopCode:stopCode,linesCode:linesCode!])
case .GetNextDepartures(let stopCode,_,_,let destinationsCode)where destinationsCode!= nil :
return(GetNextDepartures,[stopCode:stopCode,destinationsCode:destinationsCode!])
case .GetNextDepartures(let stopCode,_,_,_):
return GetNextDepartures,[stopCode:stopCode])
}
}()



有没有办法解开一个在这个语句中,可选的包含(如 if let ),并避免在此语句中显式展开:

  case .GetStops(let stopCode)where stopCode!= nil:
return(GetStops.json,[stopCode:stopCode!])


解决方案

您可以使用 .Some(x) pattern( .some(x)):

  case .GetStops(let .Some(stopCode)):
return(GetStops.json,[stopCode:stopCode])

从Swift 2(Xcode 7)开始,这可以简写为 x? pattern:

  case .GetStops(let stopCode?):
return(GetStops.json,[stopCode:stopCode])

相关值被测试为非零和解包(类似于可选绑定)。 / p>

I'm currently using Alamofire and I use an enum to describe the API I used as advised in the readme.

The endpoints are represented as follows:

public enum API {
    case GetStops(stopCode:String?)
    case GetPhysicalStops
    case GetLinesColors
    case GetNextDepartures(stopCode:String, departureCode:String?, linesCode:String?, destinationsCode:String?)
}

The optional parameters are mutually exclusive:

 public var URLRequest: NSMutableURLRequest {

        let result:(path:String, parameters:[String:AnyObject]?) = {
            switch self {
            case .GetStops(let stopCode) where stopCode != nil :
                return ("GetStops.json", ["stopCode" : stopCode!])
            case .GetStops(_):
                return ("GetStops.json", nil)
            case .GetPhysicalStops:
                 return ("GetPhysicalStops.json", nil)
            case .GetLinesColors:
                return ("GetLinesColors",nil)
            case .GetNextDepartures(let stopCode, let departureCode, _, _) where departureCode != nil:
                return ("GetNextDepartures", ["stopCode" : stopCode, "departureCode": departureCode!])
            case .GetNextDepartures(let stopCode, _, let linesCode, _) where linesCode != nil:
                return ("GetNextDepartures", ["stopCode" : stopCode, "linesCode": linesCode!])
            case .GetNextDepartures(let stopCode, _, _, let destinationsCode) where destinationsCode != nil:
                return ("GetNextDepartures", ["stopCode" : stopCode, "destinationsCode": destinationsCode!])
            case .GetNextDepartures(let stopCode,_,_,_):
                return ("GetNextDepartures",["stopCode":stopCode])
            }
            }()

Is there a way to unwrap automatically the optional contained (like if let) within the tuple and avoiding to explicity unwrap like in this statement :

case .GetStops(let stopCode) where stopCode != nil :
                    return ("GetStops.json", ["stopCode" : stopCode!])
解决方案

You can use the .Some(x) pattern (.some(x) in Swift 3):

case .GetStops(let .Some(stopCode)):
     return ("GetStops.json", ["stopCode" : stopCode])

As of Swift 2 (Xcode 7), this can be shorter written as x? pattern:

case .GetStops(let stopCode?):
     return ("GetStops.json", ["stopCode" : stopCode])

The associated value is tested to be non-nil and unwrapped (similar as in an optional binding).

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08-14 04:44