尝试用swift字典中的键字符串填充数组。
var componentArray: [String]
let dict = NSDictionary(contentsOfFile: NSBundle.mainBundle().pathForResource("Components", ofType: "plist")!)
componentArray = dict.allKeys
这将返回一个错误:'AnyObject'与string不相同
也试过
componentArray = dict.allKeys as String
but get: 'String'不能转换为[String]
当前回答
斯威夫特和斯威夫特
componentArray = Array(dict.keys) // for Dictionary
componentArray = dict.allKeys // for NSDictionary
其他回答
斯威夫特5
var dict = ["key1":"Value1", "key2":"Value2"]
let k = dict.keys
var a: [String]()
a.append(contentsOf: k)
这对我很有用。
来自Array Apple官方文档:
init(_:) -创建一个包含序列元素的数组。
宣言
Array.init<S>(_ s: S) where Element == S.Element, S : Sequence
参数
s -要转换为数组的元素序列。
讨论
You can use this initializer to create an array from any other type that conforms to the Sequence protocol...You can also use this initializer to convert a complex sequence or collection type back to an array. For example, the keys property of a dictionary isn’t an array with its own storage, it’s a collection that maps its elements from the dictionary only when they’re accessed, saving the time and space needed to allocate an array. If you need to pass those keys to a method that takes an array, however, use this initializer to convert that list from its type of LazyMapCollection<Dictionary<String, Int>, Int> to a simple [String].
func cacheImagesWithNames(names: [String]) {
// custom image loading and caching
}
let namedHues: [String: Int] = ["Vermillion": 18, "Magenta": 302,
"Gold": 50, "Cerise": 320]
let colorNames = Array(namedHues.keys)
cacheImagesWithNames(colorNames)
print(colorNames)
// Prints "["Gold", "Cerise", "Magenta", "Vermillion"]"
字典allKeys不是一个字符串。它是一个[String]，就像错误消息告诉你的那样(当然，假设键都是字符串;这正是你所说的)。
所以，要么首先将componentArray键入为[AnyObject]，因为这是它在Cocoa API中键入的方式，要么，如果你强制转换dict。allKeys，将它转换为[String]，因为这是你键入componentArray的方式。
数组从字典键在Swift
componentArray = [String] (dict.keys)
斯威夫特和斯威夫特
componentArray = Array(dict.keys) // for Dictionary
componentArray = dict.allKeys // for NSDictionary