accessing nested dictionary from api in swift

问题

Holy cow...there MUST be a better way to access formatted in

floorplan_summary: {
    bedrooms: {
        low: 1,
        high: 2,
        formatted: "1 - 2 Beds"
    }
}

than doing this:

    if data["floorplan_summary"]?["bedrooms"] != nil {
        let bedrooms = data["floorplan_summary"]?["bedrooms"] as NSDictionary
        if bedrooms["formatted"] != nil{
            self.beds = bedrooms["formatted"] as String
        }
    }

I want to just do this:

self.beds = data["floorplan_summary"]?["bedrooms"]?["formatted"] as String

..but at each level the object seems to be cast as AnyObject. Why can the compiler assume this data["floorplan_summary"]?["bedrooms"] but not the above?

How can I simplify this?

回答1:

Assuming data is NSDictionary, or [String:AnyObject]. You can:

let beds = data["floorplan_summary"]?["bedrooms"]??["formatted"] as? String // -> as String?
                                                  ^

You need extra ? because data["floorplan_summary"]?["bedrooms"] returns AnyObject??. You have to unwrap it twice.

Why it returns AnyObject??? Because data["floorplan_summary"]? is AnyObject, and AnyObject may or may not have subscript. So, the first ? means, "If it has subscript", and the second means "If subscript returns non nil".

回答2:

If you are wanting the syntax you described, I'd suggest using SwiftyJSON. It seems pretty popular, and it's all implemented in a single swift file so not hard to add it to your project. It would look something like this.

let floorPlanSummary = JSON(data: yourRawData)
self.beds = floorPlanSummery["bedrooms"]["formatted"].string

回答3:

You may be able to just invoke data.valueForKeyPath("floorplan_summary.bedrooms.formatted")

来源：https://stackoverflow.com/questions/28465390/accessing-nested-dictionary-from-api-in-swift

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