[英]Swift 4 sort dictionary by the first value
我正在使用Swift 4開發iOS應用,並且有這樣的字典:
var list = [
"US" : ["United-States","$"],
"FR" : ["France","€"],
"CN" :["China", "¥"]
]
我想根據每個字典的第一個值對基於此字典的UITableView
進行排序,以獲得以下結果:
China
France
United-States
這可能嗎?
您可以獲取字典值(數組),映射它們的第一個元素並對其進行排序:
let list = ["US" : ["United-States","$"],
"FR" : ["France","€"],
"CN" : ["China", "¥"]]
let countries = list.values.compactMap{$0.first}.sorted()
print(countries) // ["China", "France", "United-States"]
另一個選擇是為您的貨幣創建一個結構,創建一個采用鍵值對並使其符合Comparable協議的自定義初始化程序:
struct Currency: CustomStringConvertible, Comparable {
let name: String
let code: String
let symbol: String
init?(currency: (key: String, value: [String])) {
guard currency.value.count == 2 else { return nil }
self.code = currency.key
self.name = currency.value.first!
self.symbol = currency.value.last!
}
var description: String {
return "Code: \(code)\nName: \(name)\nSynmbol: \(symbol)\n"
}
}
extension Currency {
static func <(lhs: Currency, rhs: Currency) -> Bool {
return lhs.name < rhs.name
}
}
let list = ["US" : ["United-States","$"],
"FR" : ["France","€"],
"CN" :["China", "¥"]]
let currencies = list.compactMap(Currency.init).sorted()
currencies.map({print($0)})
這將打印:
代碼:CN
名稱:中國
語法:¥
代號:FR
名稱:法國
語法:€
代碼:美國
名稱:美國
語法:$
使用map
創建具有您國家的symbol
, name
和currency
的元組數組,然后按name
對該數組進行排序:
let list = ["US" : ["United-States","$"],
"FR" : ["France","€"],
"CN" : ["China", "¥"]]
let newlist = list.map { (symbol: $0.key, name: $0.value.first ?? "", currency: $0.value.dropFirst().first ?? "")}.sorted { $0.name < $1.name }
print(newlist)
[(符號:“ CN”,名稱:“ China”,貨幣:“¥”),(符號:“ FR”,名稱:“ France”,貨幣:“€”),(符號:“ US”,名稱: “美國”,貨幣:“ $”)]
這將使您輕松訪問表的所有信息:
let symbol = newlist[indexPath.row].symbol
let name = newlist[indexPath.row].name
let currency = newlist[indexPath.row].currency
要不就:
let (symbol, name, currency) = newlist[indexPath.row]
對於更復雜的字典...
您的問題之一是您的value
現在是[Any]
,因此需要有條件的強制轉換。 此外,向上突破的創作newlist
和排序。
let list = ["US" : ["United-States","$","My comment", 10],
"FR" : ["France","€", "My super comment", 20],
"CA" : ["Canada","$", "Whatever", 15],
"CN" : ["China", "¥", "Final comment", 5]]
let newlist = list.map { (symbol: $0.key,
name: $0.value.first as? String ?? "",
currency: $0.value.dropFirst().first as? String ?? "",
comment: $0.value.dropFirst(2).first as? String ?? "",
value: $0.value.dropFirst(3).first as? Int ?? 0) }
let sortedlist = newlist.sorted { $0.name < $1.name }
print(sortedlist)
[(符號:“ CA”,名稱:“ Canada”,貨幣:“ $”,注釋:“ Whatever”,值:15),(符號:“ CN”,名稱:“ China”,貨幣:“¥”,評論:“最終評論”,價值:5),(符號:“ FR”,名稱:“法國”,貨幣:“€”,評論:“我的超級評論”,價值:20),(符號:“美國” ,名稱:“美國”,貨幣:“ $”,評論:“我的評論”,值:10)]
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