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向后浏览字典以查找上次更新值的时间

swift arrays

lf_araujo · 技术社区 · 6 年前

我有一个字典数组,其中有两个感兴趣的键对。一个密钥对是日期,另一个是“investpercent”,它的值经常变化。我想知道最后一次约会是哪一次 investpercent 已更新。因此,请考虑:

var importedRecords = [
["low": "1.0", "date": "2018-04-25", "objective": "2.0", "savings": "2.0", "high": "2.0", "expenses": "1.0", "investpercent": "3.0"], 
["low": "1.0", "date": "2018-05-25", "objective": "2.0", "savings": "2.0", "high": "2.0", "expenses": "1.0", "investpercent": "3.0"], 
["low": "1.0", "date": "2018-06-25", "objective": "2.0", "savings": "2.0", "high": "2.0", "expenses": "1.0", "investpercent": "4.0"], 
["low": "1.0", "date": "2018-07-25", "objective": "2.0", "savings": "2.0", "high": "2.0", "expenses": "1.0", "investpercent": "4.0"], 
["low": "1.0", "date": "2018-08-25", "objective": "2.0", "savings": "2.0", "high": "2.0", "expenses": "1.0", "investpercent": "5.0"], 
["low": "2", "date": "2018-09-26", "objective": "2.0", "savings": "2.0", "high": "4", "expenses": "1.0", "investpercent": "5.0"]
]

现在,注意 投资百分比

var lastentry = importedRecords.suffix(1)
var lastdate: String = ""
for record in importedRecords {
    if record["investpercent"] == lastentry["investpercent"] {
        lastdate = record["date"]
    }

}

投资百分比

1 回复 | 直到 6 年前

ielyamani 6 年前

这应该可以做到,而且它使用 zip :

let reversedRecords = importedRecords.reversed()
let zipped = zip(reversedRecords.dropFirst(), reversedRecords)

if let twoDictionaries = zipped.first(where: {$0["investpercent"] != $1["investpercent"]}),
    let date = twoDictionaries.1["date"] {
    print(date)
}

它打印出来了 2018-08-25

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