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
// 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.
其他回答
let mystring:String = "indeep";
let findCharacter:Character = "d";
if (mystring.characters.contains(findCharacter))
{
let position = mystring.characters.indexOf(findCharacter);
NSLog("Position of c is \(mystring.startIndex.distanceTo(position!))")
}
else
{
NSLog("Position of c is not found");
}
如果你想使用熟悉的NSString，你可以显式地声明它:
var someString: NSString = "abcdefghi"
var someRange: NSRange = someString.rangeOfString("c")
我还不确定如何在Swift中做到这一点。
如果你想知道一个字符作为int值在字符串中的位置，使用这个:
let loc = newString.range(of: ".").location
斯威夫特5.0
public extension String {
func indexInt(of char: Character) -> Int? {
return firstIndex(of: char)?.utf16Offset(in: self)
}
}
斯威夫特4.0
public extension String {
func indexInt(of char: Character) -> Int? {
return index(of: char)?.encodedOffset
}
}
下面是一个干净的String扩展，回答了这个问题:
斯威夫特3:
extension String {
var length:Int {
return self.characters.count
}
func indexOf(target: String) -> Int? {
let range = (self as NSString).range(of: target)
guard range.toRange() != nil else {
return nil
}
return range.location
}
func lastIndexOf(target: String) -> Int? {
let range = (self as NSString).range(of: target, options: NSString.CompareOptions.backwards)
guard range.toRange() != nil else {
return nil
}
return self.length - range.location - 1
}
func contains(s: String) -> Bool {
return (self.range(of: s) != nil) ? true : false
}
}
斯威夫特2.2:
extension String {
var length:Int {
return self.characters.count
}
func indexOf(target: String) -> Int? {
let range = (self as NSString).rangeOfString(target)
guard range.toRange() != nil else {
return nil
}
return range.location
}
func lastIndexOf(target: String) -> Int? {
let range = (self as NSString).rangeOfString(target, options: NSStringCompareOptions.BackwardsSearch)
guard range.toRange() != nil else {
return nil
}
return self.length - range.location - 1
}
func contains(s: String) -> Bool {
return (self.rangeOfString(s) != nil) ? true : false
}
}
