我有一个ArraySlice<Dictionary<String, String>>
,里面只包含一个字典。如下所示:
[["high": "4", "investpercent": "6.0", "objective": "2.0", "savings": "2.0", "expenses": "1.0", "date": "2017-09-26", "low": "2"]]
然而,我想用下标操作字典,这在ArraySlice中没有实现。在典型的切片中,根据在SO中发现的问题,可以这样做:
let dictionary = ["a": 1, "b": 2, "c": 3]
var smallerDictionary: [String: Int] = [:]
for (key, value) in dictionary.dropFirst() {
smallerDictionary[key] = value
}
print(smallerDictionary) // ["a": 1, "c": 3]
我试过了,但在ArraySlice中不起作用。
发布于 2018-09-27 04:47:36
如果您的ArraySlice
名为slice
,请使用slice.first!
或slice[slice.startIndex]
访问包含的字典:
let slice: ArraySlice<[String:String]> = [["high": "4", "investpercent": "6.0", "objective": "2.0", "savings": "2.0", "expenses": "1.0", "date": "2017-09-26", "low": "2"]]
var smallerDictionary: [String: String] = [:]
for (key, value) in slice.first!.dropFirst() {
smallerDictionary[key] = value
}
print(smallerDictionary)
注意:在字典上调用dropFirst()
会给你带来不可预知的结果,因为字典是无序的。
不用说,在尝试访问所包含的字典之前,您应该确保您的ArraySlice
不为空。您可以通过显式检查slice.count > 0
、!slice.isEmpty
或正确地展开slice.first
来实现这一点。
https://stackoverflow.com/questions/52525416
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