如何从元组数组创建字典?

Let’s say I have array of objects that can be identified and I want to create dictionary from it. I can easily get tuples from my array like so:

比方说，我有一些可以被识别的对象，我想要从它创建字典。我可以很容易地从数组中获取元组，如下所示:

let tuples = myArray.map { return ($0.id, $0) }

But I can’t see initializer for dictionary to take array of tuples. Am I missing something? Do I have create extension for dictionary for this functionality (in fact it’s not hard but I thought it would be supplied by default) or there is easier way to do that?

但是我看不到字典的初始化器来获取元组数组。我遗漏了什么东西?我是否为这个功能创建了dictionary扩展(实际上它并不难，但我认为它是默认提供的)还是有更简单的方法来实现它?



There is code for extension



代码扩展

extension Dictionary
{
    public init (_ arrayOfTuples : Array<(Key, Value)>)
    {
        self.init(minimumCapacity: arrayOfTuples.count)

        for tuple in arrayOfTuples
        {
            self[tuple.0] = tuple.1
        }
    }
}

3 个解决方案

#1

Depending on what you want to do, you could:

取决于你想做什么，你可以:

let tuples = [(0, "0"), (1, "1"), (1, "2")]
var dictionary = [Int: String]()

Option 1: replace existing keys

选项1:替换现有的键

tuples.forEach {
    dictionary[$0.0] = $0.1
}    
print(dictionary) //prints [0: "0", 1: "2"]

Option 2: Don't allow repeting keys

选项2:不允许重复键

enum Errors: Error {
    case DuplicatedKeyError
}

do {
    try tuples.forEach {
        guard dictionary.updateValue($0.1, forKey:$0.0) == nil else { throw Errors.DuplicatedKeyError }
    }
    print(dictionary)
} catch {
    print("Error") // prints Error
}

#2

A generic approach:

/**
 * Converts tuples to dict
 */
func dict<K,V>(_ tuples:[(K,V)])->[K:V]{
    var dict:[K:V] = [K:V]()
    tuples.forEach {dict[$0.0] = $0.1}
    return dict
}

Functional programming update:

函数式编程更新:

func dict<K,V>(tuples:[(K,V)])->[K:V]{
    return tuples.reduce([:]) {
       var dict:[K:V] = $0
       dict[$1.0] = $1.1   
       return dict
    }
}

#3

Improved @GitSync answer using an extension.

使用扩展名改进@GitSync应答。

extension Array {
    func toDictionary<K,V>() -> [K:V] where Iterator.Element == (K,V) {
        return self.reduce([:]) {
            var dict:[K:V] = $0
            dict[$1.0] = $1.1
            return dict
        }
    }
}