如何在Swift中將字典值數組打印成漂亮的字符串

Question

我有一組routine對象，它們的定義為：

struct Routine {
    let routineName: String
    let routineExercisesAndSets: [String: Int]
}

let routines: [Routine] = {
    let firstRoutine = Routine(routineName: "Legs", routineExercisesAndSets: ["Squats":4,"Lunges":4,"Calf Raises":4])

    let secondRoutine = Routine(routineName: "Chest", routineExercisesAndSets: ["Bench Press":4,"Press Ups":4,"Flyes":4,"Inclined Bench Press":4])

    let thirdRoutine = Routine(routineName: "Arms", routineExercisesAndSets: ["Bicep Curls":4,"Hammer Curls":4,"Preacher Curls":4,"Tricep Extension":4,"Tricep Dips":4])

    return [firstRoutine, secondRoutine, thirdRoutine]
}()

我正在嘗試將它們的routineExercisesAndSets數組作為詳細文本返回到UITableViewCell中，當使用array.description函數時，我在tableView中得到此結果

我的問題是，我該如何遍歷例程對象並打印出一個“漂亮的”格式的字符串，看起來像這樣：

"Calf Raises x 4, Squats x 4, Lunges x 4..."

我可以使用以下代碼在新行上打印出各個鍵，值對：

for i in routines{
    for (key, value) in (i.routineExercisesAndSets)! {
        print("\(key) x \(String(value))")
    }
}

產生：

Calf Raises x 4 Squats x 4 Lunges x 4 Bench Press x 4 Press Ups x 4 Flyes x 4 Inclined Bench Press x 4 Tricep Extension x 4 Tricep Dips x 4 Preacher Curls x 4 Hammer Curls x 4 Bicep Curls x 4

但是我想按它們的父對象對它們進行分組，以便將例行練習顯示在同一行上，因此看起來像示例"Calf Raises x 4, Squats x 4, Lunges x 4..." 。

Answer 1

您可以通過鏈接map和joined操作來構造單個String描述給定練習的練習字典。 例如

for routine in routines {
    print("Routine:", routine.routineName)
    print("--------------")
    print(routine.routineExercisesAndSets
        .map { $0 + " x \($1)" }
        .joined(separator: ", "))
    print()
}
/* Routine: Legs
   --------------
   Calf Raises x 4, Squats x 4, Lunges x 4

   Routine: Chest
   --------------
   Bench Press x 4, Press Ups x 4, Flyes x 4, Inclined Bench Press x 4

   Routine: Arms
   --------------
   Tricep Extension x 4, Tricep Dips x 4, Preacher Curls x 4, Hammer Curls x 4, Bicep Curls x 4 

                   */

此外，您可以將它們實現為Routine的計算description屬性的返回，而不是在每次使用時顯式執行這些“表示”轉換，這是使Routine符合CustomStringConvertible ：

extension Routine: CustomStringConvertible {
    var description: String {
        return routineName + ":\n" + routineExercisesAndSets
            .map { $0 + " x \($1)" }
            .joined(separator: ", ")
    }
}

for routine in routines {
    print(routine) /* uses Routine:s implementation of 'CustomStringConvertible',
                      the computed property 'description`, specifically           */
    print()
}
/* Legs:
   Calf Raises x 4, Squats x 4, Lunges x 4

   Chest:
   Bench Press x 4, Press Ups x 4, Flyes x 4, Inclined Bench Press x 4

   Arms:
   Tricep Extension x 4, Tricep Dips x 4, Preacher Curls x 4, Hammer Curls x 4, Bicep Curls x 4

                   */

---

鑒於您在下面的評論，似乎Routine的屬性routineName和Routine routineExercisesAndSets是可選的。 如果是這種情況，您自然需要在訪問它們（可能存在的）值之前處理它們的展開。 例如，如果兩個屬性中的任何一個為nil ，則返回一個空的description ，否則返回組合的例程名稱和詳細信息描述（如上面的非可選示例所述）：

struct Routine {
    let routineName: String?
    let routineExercisesAndSets: [String: Int]?
}

extension Routine: CustomStringConvertible {
    var description: String {
        guard let name = routineName, let details = routineExercisesAndSets else { return "" }
        return name + ":\n" + details.map { $0 + " x \($1)" }.joined(separator: ", ")
    }
}

Answer 2

首先，讓Routine符合CustomStringConvertible

extension Routine: CustomStringConvertible {
    var description: String {
        return routineExercisesAndSets.map { $0 + " x " + $1.description }.joined(separator: ", ")
    }
}

現在您可以輕松編寫

routines.forEach { print($0) }

結果

Calf Raises x 4, Squats x 4, Lunges x 4
Bench Press x 4, Press Ups x 4, Flyes x 4, Inclined Bench Press x 4
Tricep Extension x 4, Tricep Dips x 4, Preacher Curls x 4, Hammer Curls x 4, Bicep Curls x 4

或給定一個UITableViewCell ...

let cell: UITableViewCell = ...
let routine: Routine = ...
cell.detailTextLabel?.text = routine.description