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
extension String{
func contains(find: String)->Bool{
return self.range(of: find) != nil
}
}
func check(n:String, h:String)->Int{
let n1 = n.lowercased()
let h1 = h.lowercased()//lowercase to make string case insensitive
var pos = 0 //postion of substring
if h1.contains(n1){
// checking if sub string exists
if let idx = h1.firstIndex(of:n1.first!){
let pos1 = h1.distance(from: h1.startIndex, to: idx)
pos = pos1
}
return pos
}
else{
return -1
}
}
print(check(n:"@", h:"hithisispushker,he is 99 a good Boy"))//put substring in n: and string in h
其他回答
// 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.
String是NSString的桥接类型，add
import Cocoa
到你的swift文件，并使用所有“旧”的方法。
字符串{
//Fucntion to get the index of a particular string
func index(of target: String) -> Int? {
if let range = self.range(of: target) {
return characters.distance(from: startIndex, to: range.lowerBound)
} else {
return nil
}
}
//Fucntion to get the last index of occurence of a given string
func lastIndex(of target: String) -> Int? {
if let range = self.range(of: target, options: .backwards) {
return characters.distance(from: startIndex, to: range.lowerBound)
} else {
return nil
}
}
}
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)
