Question

我目前有一个功能，该功能可以基于一些初步信息从firebase提取图像，并且在相同的树级别上，图像是时间戳值（针对每个图像）。我一直无法获得价值，只能获得Optional(123131.432432)，这当然不是我所需要的。

以下是函数：

    func fetchAllPostImages() {
    print("fetchAllPostImages function")
    self.ref.child("Posts").child(self.userID).child(self.postNum).child("Images").observe(.childAdded, with: { snapshot in
        var snapshotUrl = snapshot.childSnapshot(forPath: "ImageUrl")
        var timeStampData = snapshot.childSnapshot(forPath: "timeStamp").value

        print("fhdsjaklhfkjdsfksahdjksfjlashfkljdhs")
        print(snapshot.childSnapshot(forPath: "ImageUrl"))
        print(snapshot.childSnapshot(forPath: "timeStamp").value, "timestamp123")
        print(snapshotUrl.value as? [String: String], "value")

            if let urlValue = snapshotUrl.value {
                print("jkdhsjbbvcbcbcbccbbbbbbbbbbbbbbb")
                let snapShotValue = [ "ImageUrl" : urlValue]
                let timeStampVal = ["timeStamp" : timeStampData]

                print(timeStampVal, "dsfaf")
                for (_, value) in snapShotValue {

                    if let imageURL = URL(string: value as! String) {
                        print(imageURL, "image url here")
                        do {
                            let imageAsData = try Data(contentsOf: imageURL)
                            let image = UIImage(data: imageAsData)
                            var timeStamp = 0.0
                            self.arrayOfImgObj.append(Media(image: image!, timeStamp: timeStamp))
                            self.tableView.reloadData()
                            print(self.arrayOfImgObj.count, "array.count")
                        } catch {
                            print("imageURL was not able to be converted into data")
                        }
                    }
                }
        }
    })
}

所以我能够执行以下操作，但这似乎可行，但是在tableView中，我看到了与以前相同的Optional（5421432.43214）。即使我打印时，它也需要两倍的价值。

for (value, timeValue) in zip(snapShotValue.values, timeStampVal) {
    if let imageURL = URL(string: value as! String) {
        print(imageURL, "image url here")
        do {
            let imageAsData = try Data(contentsOf: imageURL)
            let image = UIImage(data: imageAsData)
            var timeStampValue = timeValue as! Double
            print(timeStampValue, "fgsdfg")
            let timeStamp: Double = timeStampValue
            self.arrayOfImgObj.append(Media(image: image!, timeStamp: timeStamp))
            self.tableView.reloadData()
            print(self.arrayOfImgObj.count, "array.count")
        } catch {
            print("imageURL was not able to be converted into data")
        }
    }
}

如何将包装在可选内容中的timeStamp值转换为双精度值？

Answer 1

基本上，最简单的方法是将Int添加到调用arrayOfImg[indexPath.row].timeStamp的位置。所以它应该像这样：

let timeStamp = "\(Int(arrayOfImg[indexPath.row].timeStamp))"

Answer 2

尝试更换

let timeStamp: Double = timeStampValue

使用

guard let timeStamp = timeStampValue as Double else { return }

这将安全地打开您的可选内容，并将值转换为Double。

如何将包装在可选参数中的timeStamp值转换为double？

2 个答案: