如何在Swift中从字典中获得最低和最高价值

Question

I am facing a problem in getting the values to make the desired combination. I am using a filter screen in my app. I asked this question to get the first and last element from the question How to put the of first and last element of Array in Swift and it is working but the problem is in my FiterVC first I selected the option $400 - $600 and then I selected the $200 - $400 . After selecting I am getting these values in my currentFilter variable.

private let menus = [

    ["title": "Price", "isMultiSelection": true, "values": [
        ["title": "$00.00 - $200.00"],
        ["title": "$200.00 - $400.00"],
        ["title": "$400.00 - $600.00"],
        ["title": "$600.00 - $800.00"],
        ["title": "$800.00 - $1000.00"],
        ]],
    ["title": "Product Rating", "isMultiSelection": true, "values": [
        ["title": "5"],
        ["title": "4"],
        ["title": "3"],
        ["title": "2"],
        ["title": "1"]
        ]],
    ["title": "Arriving", "isMultiSelection": true, "values": [
        ["title": "New Arrivials"],
        ["title": "Coming Soon"]
        ]]
]

private var currentFilters = [String:Any]()

Selecting values in didSelect method:-

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    if tableView === self.menuTableView {
        self.currentSelectedMenu = indexPath.row
        self.menuTableView.reloadData()
        self.valueTableView.reloadData()
    }
    else {
        if let title = self.menus[self.currentSelectedMenu]["title"] as? String, let values = self.menus[self.currentSelectedMenu]["values"] as? [[String:Any]], let obj = values[indexPath.row]["title"] as? String {
            if let old = self.selectedFilters[title] as? [String], let isAllowedMulti = self.menus[self.currentSelectedMenu]["isMultiSelection"] as? Bool, !old.isEmpty, !isAllowedMulti {
                var temp = old
                if old.contains(obj), let index = old.index(of: obj) {
                    temp.remove(at: index)
                }
                else {
                    temp.append(obj)     
                }
                self.selectedFilters[title] = temp
            }
            else {
                self.selectedFilters[title] = [obj]
            }
            self.valueTableView.reloadData()
        }
    }
}

And on Apply button click:-

@IBAction func applyButtonAction(_ sender: UIButton) {
    self.delegate?.didSelectedFilters(self, with: self.selectedFilters)
    printD(self.selectedFilters)
    self.dismiss(animated: true, completion: nil)
}

When I am printing the selectedFilters I am getting these values:-

currentFilters ["Price": ["$400.00 - $600.00", "$200.00 - $400.00"]]

And by using this method I am getting the first and last value from dictionary like this:-

if let obj = currentFilters["Price"] as? [String] {
   self.priceRange = obj
   printD(self.priceRange)

   let first = priceRange.first!.split(separator: "-").first!
   let last = priceRange.last!.split(separator: "-").last!
   let str = "\(first)-\(last)"
   let str2 = str.replacingOccurrences(of: "$", with: "", options: NSString.CompareOptions.literal, range: nil)
   newPrice = str2
   printD(newPrice)
}

The result is :-

400.00 - 400.00

but what I actually want is 200 - 600 . How can I do this. Please help?

Answer 1

However there are many solutions available to this problem but simplest and most relevant solution is highlighted here:

let min = 1000, max = 0
if let obj = currentFilters["Price"] as? [String] {
   self.priceRange = obj
   printD(self.priceRange)

   for str in obj{
     let first = str.split(separator: "-").first!.replacingOccurrences(of: "$", with: "", options:
            NSString.CompareOptions.literal, range: nil)
     let last = str.split(separator: "-").last!.replacingOccurrences(of: "$", with: "", options:
            NSString.CompareOptions.literal, range: nil)
     if Int(first) < min{
       min = first
     }
     if Int(last) > max{
       max = last
     }
   }
   let str = "\(min)-\(max)"
   newPrice = str
   printD(newPrice)
}

Answer 2

You can use an enum with functions to load your prices ranges instead of using directly Strings.

enum PriceRange: String {
    case
    low     = "200 - 400",
    high    = "400 - 600"

    static let priceRanges = [low, high]

    func getStringValue() -> String {
        return self.rawValue
    }

    func getMinValueForRange(stringRange: String) -> Int? {
        switch stringRange {
        case "200 - 400":
            return 200;

        case "400 - 600":
            return 400;
        default:
            return nil
        }
    }

    func getMaxValueForRange(stringRange: String) -> Int? {
        switch stringRange {
        case "200 - 400":
            return 400;

        case "400 - 600":
            return 600;
        default:
            return nil
        }
    }

}

Then you can use/add functions to get the result that you are looking for.

Answer 3

We can do by steps -

1 - Get the price ranges from the dictionary

2 - Iterate over those price ranges

3 - Split the range by "-" and check if the prices count is 2 else this is an invalid price range

4 - Get the numeric components from the two prices and then compare from the previously saved min and max values and update them accordingly

Try this -

if let priceRanges = currentFilters["Price"] as? [String] { // Extract the price ranges from dictionary

    var minValue: Double? // Holds the min value
    var maxValue: Double? // Holds the max value

    for priceRange in priceRanges { Iterate over the price ranges

        let prices = priceRange.split(separator: "-") // Separate price range by "-"

        guard prices.count == 2 else { // Checks if there are 2 prices else price range is invalid
            print("invalid price range")
            continue // skip this price range when invalid
        }

        let firstPrice = String(prices[0]).numericString // Extract numerics from the first price
        let secondPrice = String(prices[1]).numericString // Same for the second price

        if let value = Double(firstPrice) { // Check if the price is valid amount by casting it to double
            if let mValue = minValue { // Check if we have earlier saved a minValue from a price range
                minValue = min(mValue, value) // Assign minimum of current price and earlier save min price
            } else {
                minValue = value // Else just save this price to minValue
            }
        }

        if let value = Double(secondPrice) { // Check if the price is valid amount by casting it to double
            if let mValue = maxValue { // Check if we have earlier saved a maxValue from a price range
                maxValue = max(mValue, value) // Assign maximum of current price and earlier save max price
            } else {
                maxValue = value // Else just save this price to maxValue
            }
        }
    }
    if let minV = minValue, let maxV = maxValue { // Check if we have a min and max value from the price ranges
        print("\(minV) - \(maxV)")
    } else {
        print("unable to find desired price range") // Else print this error message
    }
}

extension String {

    /// Returns a string with all non-numeric characters removed
    public var numericString: String {
        let characterSet = CharacterSet(charactersIn: "01234567890.").inverted
        return components(separatedBy: characterSet)
            .joined()
    }
}

Answer 4

Here's the small solution of your problem. It all breaks down to that: you get all the values from your filters, and then iterating over getting all the values from it. That way you avoid comparing the pairs and instead comparing the exact values.

let currentFilters =  ["Price": ["$400.00 - $600.00", "$200.00 - $400.00"]]
let ranges = currentFilters["Price"]!
var values: [Double] = []
ranges.forEach { range in // iterate over each range
    let rangeValues = range.split(separator: "-")
    for value in rangeValues { // iterate over each value in range
        values.append(Double( // cast string value to Double
            String(value)
                .replacingOccurrences(of: " ", with: "")
                .replacingOccurrences(of: "$", with: "")
        )!)
    }
}

let min = values.min() // prints 200
let max = values.max() // prints 600