如何使用Swift 3在MutableArray的標頭中在TableView中創建字母部分

Question

我正在嘗試向表中添加節，但是我無法將MutableArray （包含60個值的database ）中的第一個字母放入dictionary 。 我想創建第一個字母為標題的字母sections並以該字母開頭的所有值創建sections的行數。

我的代碼：

func getSectionsFromData() -> Dictionary<Character,String> {

    var sectionDictionary = Dictionary<Character, String>()

    let crime: CrimesInfo = marrCrimesNames.object(at: 0) as! CrimesInfo
    var crimeFirstLetter: AnyObject
    let crimeName = crime.Name

    for crime in marrCrimesNames {
        crimeFirstLetter = crimeName.characters.first! as AnyObject
        print(crimeFirstLetter)
    }
    return sectionDictionary
}

輸出：

“ A” // 60次

Answer 1

在

for crime in marrCrimesNames {
    crimeFirstLetter = crimeName.characters.first! as AnyObject
    print(crimeFirstLetter)
}

你不實際使用的crime變量，而不是您只使用crimeName這就是為什么你得到“A”的所有時間。

試試吧

for crime in marrCrimesNames {
    crimeFirstLetter = crime.Name.characters.first! as AnyObject
    print(crimeFirstLetter)
}

現在創建一個像這樣的字典：

let dict = ["A" : ["Aname1", "Aname2", "Aname3"], "B" : ["Bname1", "Bname2", "Bname3"]]

從這樣的數組中：

let array = ["Aname1", "Aname2", "Aname3", "Bname1", "Bname2", "Bname3"]

您可以使用以下代碼：

let dict = ["A" : ["Aname1", "Aname2", "Aname3"], "B" : ["Bname1", "Bname2", "Bname3"]]

let characters = Array(Set(array.flatMap({ $0.characters.first })))

var result = [String: [String]]()

for character in characters.map({ String($0) }) {
    result[character] = array.filter({ $0.hasPrefix(character) })
}

print(result) // output: ["B": ["Bname1", "Bname2", "Bname3"], "A": ["Aname1", "Aname2", "Aname3"]]