是时候承认失败了……
在Objective-C中，我可以使用如下内容:
NSString* str = @"abcdefghi";
[str rangeOfString:@"c"].location; // 2
在Swift中，我看到了类似的东西:
var str = "abcdefghi"
str.rangeOfString("c").startIndex
.．.但这只是给了我一个字符串。索引，我可以使用它下标回原始字符串，但不能从中提取位置。
FWIW，字符串。Index有一个名为_position的私有ivar，其中有正确的值。我只是不明白怎么会暴露出来。
我知道我自己可以很容易地将其添加到String中。我更好奇在这个新的API中我缺少了什么。
当前回答
最简单的方法是:
在Swift 3中:
var textViewString:String = "HelloWorld2016"
guard let index = textViewString.characters.index(of: "W") else { return }
let mentionPosition = textViewString.distance(from: index, to: textViewString.endIndex)
print(mentionPosition)
其他回答
斯威夫特3
extension String {
func substring(from:String) -> String
{
let searchingString = from
let rangeOfSearchingString = self.range(of: searchingString)!
let indexOfSearchingString: Int = self.distance(from: self.startIndex, to: rangeOfSearchingString.upperBound )
let trimmedString = self.substring(start: indexOfSearchingString , end: self.count)
return trimmedString
}
}
// Using Swift 4, the code below works.
// The problem is that String.index is a struct. Use dot notation to grab the integer part of it that you want: ".encodedOffset"
let strx = "0123456789ABCDEF"
let si = strx.index(of: "A")
let i = si?.encodedOffset // i will be an Int. You need "?" because it might be nil, no such character found.
if i != nil { // You MUST deal with the optional, unwrap it only if not nil.
print("i = ",i)
print("i = ",i!) // "!" str1ps off "optional" specification (unwraps i).
// or
let ii = i!
print("ii = ",ii)
}
// Good luck.
你可以用这个找到字符串中一个字符的索引号:
var str = "abcdefghi"
if let index = str.firstIndex(of: "c") {
let distance = str.distance(from: str.startIndex, to: index)
// distance is 2
}
你也可以像这样在一个字符串中找到一个字符的索引，
extension String {
func indexes(of character: String) -> [Int] {
precondition(character.count == 1, "Must be single character")
return self.enumerated().reduce([]) { partial, element in
if String(element.element) == character {
return partial + [element.offset]
}
return partial
}
}
}
它在[String]中给出结果。距离ie。(Int)
"apple".indexes(of: "p") // [1, 2]
"element".indexes(of: "e") // [0, 2, 4]
"swift".indexes(of: "j") // []
我玩以下的游戏
extension String {
func allCharactes() -> [Character] {
var result: [Character] = []
for c in self.characters {
result.append(c)
}
return
}
}
直到我理解提供的一个，现在它只是字符数组
和
let c = Array(str.characters)
