我是Swift的新手,下面的功能对此有问题。我正在使用SWIFT 5 / Xcode 11.3。该功能旨在删除元音之前的所有字母。例如,“ Brian”将返回“ ian”,“ Bill”将返回“ ill”,等等。我在下面的2行中得到了错误。
import Foundation
func shortNameFromName(_ name: String) -> String {
// Definition of characters
let vowels = CharacterSet(charactersIn: "aeiou")
var shortName = ""
let start = name.startIndex
// Loop through each character in name
for number in 0..<name.count {
// If the character is a vowel, remove all characters before current index position
if vowels.contains(name[name.index(start, offsetBy: number)]) == true { //**ERROR: Cannot convert value of type 'Character' to expected argument type 'Unicode.Scalar'**
var shortName = name.remove(at: shortName.index(before: shortName.number)) //**ERROR: Cannot use mutating member on immutable value: 'name' is a 'let' constant**
}
}
//convert returned value to lowercase
return name.lowercased()
}
var str = "Brian" // Expected result is "ian"
shortNameFromName(str)
func drop(while predicate: (Character) throws -> Bool) rethrows -> Substring
当字符串“ aeiou”不包含字符时,可以使用collection的方法并返回子字符串:
func shortName(from name: String) -> String { name.drop{ !"aeiou".contains($0) }.lowercased() }
shortName(from: "Brian") // "ian"
shortName(from: "Bill") // "ill"
关于代码中的问题,请通过以下代码检查注释:
func shortName(from name: String) -> String {
// you can use a string instead of a CharacterSet to fix your first error
let vowels = "aeiou"
// to fix your second error you can create a variable from your first parameter name
var name = name
// you can iterate through each character using `for character in name`
for character in name {
// check if the string with the vowels contain the current character
if vowels.contains(character) {
// and remove the first character from your name using `removeFirst` method
name.removeFirst()
}
}
// return the resulting name lowercased
return name.lowercased()
}
shortName(from: "Brian") // "ian"
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