我从我尝试升级到最新 Swift 版本的项目中的这部分代码中得到一个“表达式类型不明确，没有更多上下文”。我似乎想不通。我尝试了不同的东西，但无法让它工作。

问题出在这行的语法上

let imageToDeleteParameters  = imagesToDelete.map { ["id": $0.id, "url": $0.url.absoluteString, "_destroy": true] }

完整代码：

extension TutorialCreationRequest: WebserviceParametrable {
    func toParameters() -> [String: AnyObject] {
        let imageParameters = images.map { ["url": $0] }
        let imageToDeleteParameters  = imagesToDelete.map { ["id": $0.id, "url": $0.url.absoluteString, "_destroy": true] }
        return [
            "title": title,
            "is_draft": isDraft,
            "difficulty": difficulty,
            "duration": duration,
            "cost": cost,
            "user_id": userId,
            "description": description,
            "to_sell": toSell,
            "images": [imageParameters, imageToDeleteParameters].flatMap { $0 }
        ]
    }
}