[英]In Swift 2, how to cast a JSON array to [Int32]
我有以下代碼可讀取JSON文件,然后將其數組轉換為[Float32]或[Int32]
let location = NSString(string:"/Users/myname/Documents/test.js").stringByExpandingTildeInPath
let rawData = NSData(contentsOfFile: location)
let modelData = try? NSJSONSerialization.JSONObjectWithData(rawData!, options: NSJSONReadingOptions.AllowFragments)
let dict = modelData as! NSDictionary
guard let vertices = dict["vertices"] as? [Float32] else {
print("error casting vertices")
return
}
guard let indices = dict["faces"] as? [Int32] else {
print("error casting indices")
return
}
JSON文件的內容為:
{
"vertices" : [1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9],
"faces" : [0,1,2]
}
JSON文件已成功加載並解析,但是,將vertices
為[Float32]
成功,而將faces
為[Int32]
失敗。 反正有將faces
投射到[Int32]
嗎?
只需將其轉換為[Int]而不是[Int32]。 您可以像這樣檢查類型
dict["faces"] is [Int]
當let indices = dict["faces"]
將創建類型為Array<Double>
indices
數組,因此無法將其[Int32]
為[Int32]
或什至[Int]
。 您可以嘗試以下代碼將其轉換為[Int32]
let faces = dict["faces"]! as [AnyObject]
let intFaces = (faces as! [Int]).map({Int32($0)})
intFaces
的類型為[Int32]
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