Swift 中的字典迭代

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我们可以使用多种方法在 Swift 中迭代字典。您也可以迭代字典的键和值。

我们将使用以下不同的方法来迭代字典：

• 使用 for-in 循环

• 迭代字典中的所有键

• 迭代字典中的所有值

• 使用 enumerated() 方法迭代所有元素

使用 for-in 循环

大多数情况下，我们使用 for-in 循环来迭代字典。使用 for-in 循环，您可以像下面这样迭代字典的所有元素：

语法

for (key, value) in dictionary {

}

在语法中，key 和 value 是将分别保存当前键和值的变量的名称。

示例

import Foundation
let colorsDictionary = [
   "aliceblue": "#f0f8ff",
   "antiquewhite": "#faebd7",
   "aqua": "#00ffff",
   "aquamarine": "#7fffd4",
   "azure": "#f0ffff",
   "beige": "#f5f5dc",
   "bisque": "#ffe4c4",
   "black": "#000000",
   "blanchedalmond": "#ffebcd",
   "blue": "#0000ff",
   "blueviolet": "#8a2be2",
   "brown": "#a52a2a"
]
for (colorName, colorValue) in colorsDictionary {
   print("Name: \(colorName) and its hex code: \(colorValue)")
}

输出

Name: brown and its hex code: #a52a2a
Name: bisque and its hex code: #ffe4c4
Name: blueviolet and its hex code: #8a2be2
Name: aqua and its hex code: #00ffff
Name: aliceblue and its hex code: #f0f8ff
Name: aquamarine and its hex code: #7fffd4
Name: azure and its hex code: #f0ffff
Name: beige and its hex code: #f5f5dc
Name: blanchedalmond and its hex code: #ffebcd
Name: blue and its hex code: #0000ff
Name: antiquewhite and its hex code: #faebd7
Name: black and its hex code: #000000

在上面的示例中，我们创建了一个字典来定义一些颜色及其名称和十六进制值。使用 for-in 循环，逐个迭代所有元素，顺序未指定。它以 (键, 值) 对的形式给出元素。

迭代所有键

如果您想一次访问或迭代所有键，可以使用“keys”属性。此属性返回一个字符串类型的数组，其中包含字典的所有键。

示例

import Foundation
let colorsDictionary = ["aliceblue": "#f0f8ff",
   "antiquewhite": "#faebd7",
   "aqua": "#00ffff",
   "aquamarine": "#7fffd4",
   "azure": "#f0ffff",
   "beige": "#f5f5dc",
   "bisque": "#ffe4c4",
   "black": "#000000",
   "blanchedalmond": "#ffebcd",
   "blue": "#0000ff",
   "blueviolet": "#8a2be2",
   "brown": "#a52a2a"
]
for key in colorsDictionary.keys {
    print("Key: \(key)")
}

输出

Key: brown
Key: antiquewhite
Key: bisque
Key: beige
Key: black
Key: aqua
Key: azure
Key: aliceblue
Key: blue
Key: blueviolet
Key: aquamarine
Key: blanchedalmond

在上面的示例中，我们创建了一个字典来定义一些颜色及其名称和十六进制值。使用 for-in 循环迭代字典的所有键。

迭代所有值

如果您想一次访问或迭代所有值，可以使用“values”属性。此属性返回一个字符串类型的数组，其中包含字典的所有值。

示例

import Foundation
let colorsDictionary = ["aliceblue": "#f0f8ff",
   "antiquewhite": "#faebd7",
   "aqua": "#00ffff",
   "aquamarine": "#7fffd4",
   "azure": "#f0ffff",
   "beige": "#f5f5dc",
   "bisque": "#ffe4c4",
   "black": "#000000",
   "blanchedalmond": "#ffebcd",
   "blue": "#0000ff",
   "blueviolet": "#8a2be2",
   "brown": "#a52a2a"
]
for value in colorsDictionary.values {
    print("Value: \(value)")
}

输出

Value: #00ffff
Value: #f0f8ff
Value: #f5f5dc
Value: #000000
Value: #f0ffff
Value: #ffebcd
Value: #7fffd4
Value: #ffe4c4
Value: #0000ff
Value: #faebd7
Value: #a52a2a
Value: #8a2be2

结论

我们可以迭代 Swift 中字典的元素、键和值。字典提供“keys”属性来访问所有键的数组。同样，“values”属性提供所有值的数组。

您可以使用 for-in 循环和其他方法迭代字典。但请记住，元素的顺序未指定。但是，使用 enumerated() 函数，您仍然可以在访问元素时跟踪其索引。