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
在swift 2.0中
var stringMe="Something In this.World"
var needle="."
if let idx = stringMe.characters.indexOf(needle) {
let pos=stringMe.substringFromIndex(idx)
print("Found \(needle) at position \(pos)")
}
else {
print("Not found")
}
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");
}
extension String {
// MARK: - sub String
func substringToIndex(index:Int) -> String {
return self.substringToIndex(advance(self.startIndex, index))
}
func substringFromIndex(index:Int) -> String {
return self.substringFromIndex(advance(self.startIndex, index))
}
func substringWithRange(range:Range<Int>) -> String {
let start = advance(self.startIndex, range.startIndex)
let end = advance(self.startIndex, range.endIndex)
return self.substringWithRange(start..<end)
}
subscript(index:Int) -> Character{
return self[advance(self.startIndex, index)]
}
subscript(range:Range<Int>) -> String {
let start = advance(self.startIndex, range.startIndex)
let end = advance(self.startIndex, range.endIndex)
return self[start..<end]
}
// MARK: - replace
func replaceCharactersInRange(range:Range<Int>, withString: String!) -> String {
var result:NSMutableString = NSMutableString(string: self)
result.replaceCharactersInRange(NSRange(range), withString: withString)
return result
}
}
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
}
}
斯威夫特5
查找子字符串的索引
let str = "abcdecd"
if let range: Range<String.Index> = str.range(of: "cd") {
let index: Int = str.distance(from: str.startIndex, to: range.lowerBound)
print("index: ", index) //index: 2
}
else {
print("substring not found")
}
查找字符索引
let str = "abcdecd"
if let firstIndex = str.firstIndex(of: "c") {
let index: Int = str.distance(from: str.startIndex, to: firstIndex)
print("index: ", index) //index: 2
}
else {
print("symbol not found")
}
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
