Try this:

尝试这个：

var a = "Cash"
var b = "cash"
let result: NSComparisonResult = a.compare(b, options: NSStringCompareOptions.CaseInsensitiveSearch, range: nil, locale: nil)

// You can also ignore last two parameters(thanks 0x7fffffff)
//let result: NSComparisonResult = a.compare(b, options: NSStringCompareOptions.CaseInsensitiveSearch)

result is type of NSComparisonResult enum:

结果是 NSComparisonResult 枚举类型：

enum NSComparisonResult : Int {

    case OrderedAscending
    case OrderedSame
    case OrderedDescending
}

So you can use if statement:

所以你可以使用 if 语句：

if result == .OrderedSame {
    println("equal")
} else {
    println("not equal")
}

Try this :

尝试这个 ：

For older swift:

对于年长的斯威夫特：

var a : String = "Cash"
var b : String = "cash"

if(a.caseInsensitiveCompare(b) == NSComparisonResult.OrderedSame){
    println("voila")
}

Swift 3+

斯威夫特 3+

var a : String = "Cash"
var b : String = "cash"

if(a.caseInsensitiveCompare(b) == .orderedSame){
    print("voila")
}

Use caseInsensitiveComparemethod:

使用caseInsensitiveCompare方法：

let a = "Cash"
let b = "cash"
let c = a.caseInsensitiveCompare(b) == .orderedSame
print(c) // "true"

ComparisonResulttells you which word comes earlier than the other in lexicographic order (i.e. which one comes closer to the front of a dictionary). .orderedSamemeans the strings would end up in the same spot in the dictionary

比较结果会告诉您哪个词在词典顺序中比另一个词出现得早（即哪个词更靠近字典的前面）。.orderedSame意味着字符串将在字典中的同一位置结束

if a.lowercaseString == b.lowercaseString {
    //Strings match
}

Could just roll your own:

可以自己推出：

func equalIgnoringCase(a:String, b:String) -> Bool {
    return a.lowercaseString == b.lowercaseString
}

CORRECT WAY:

正确方法：

let a: String = "Cash"
let b: String = "cash"

if a.caseInsensitiveCompare(b) == .orderedSame {
    //Strings match 
}

Please note:ComparisonResult.orderedSame can also be written as .orderedSame in shorthand.

请注意：ComparisonResult.orderedSame 也可以简写为 .orderedSame。

OTHER WAYS:

其他方法：

a.

一种。

if a.lowercased() == b.lowercased() {
    //Strings match 
}

b.

湾

if a.uppercased() == b.uppercased() {
    //Strings match 
}

c.

C。

if a.capitalized() == b.capitalized() {
    //Strings match 
}

localizedCaseInsensitiveContains: Returns whether the receiver contains a given string by performing a case-insensitive, locale-aware search

localizedCaseInsensitiveContains：通过执行不区分大小写的区域设置搜索来返回接收器是否包含给定的字符串

if a.localizedCaseInsensitiveContains(b) {
    //returns true if a contains b (case insensitive)
}

Edited:

编辑：

caseInsensitiveCompare: Returns the result of invoking compare(_:options:) with NSCaseInsensitiveSearch as the only option.

caseInsensitiveCompare：返回调用 compare(_:options:) 的结果，其中 NSCaseInsensitiveSearch 作为唯一选项。

if a.caseInsensitiveCompare(b) == .orderedSame {
    //returns true if a equals b (case insensitive)
}

Phone numbers comparison example; using swift 4.2

电话号码比较示例；使用 Swift 4.2

var selectPhone = [String]()

if selectPhone.index(where: {
var a = “Cash”
var b = “CASh”

if a.uppercaseString == b.uppercaseString{
  //DO SOMETHING
}
.caseInsensitiveCompare(contactsList[indexPath.row].phone!) == .orderedSame}) != nil {
    print("Same value")
} else {
    print("Not the same")
}

You could also make all the letters uppercase (or lowercase) and see if they are the same.

您还可以将所有字母大写（或小写），看看它们是否相同。

extension String{
  func equalsIgnoreCase(string:String) -> Bool{
    return self.uppercaseString == string.uppercaseString
  }
}

if "Something ELSE".equalsIgnoreCase("something Else"){
  print("TRUE")
}

This will make both variables as ”CASH”and thus they are equal.

这将使两个变量相同”CASH”，因此它们相等。

You could also make a Stringextension

你也可以做一个String扩展

extension String {

    func compare(_ with : String)->Bool{
        return self.caseInsensitiveCompare(with) == .orderedSame
    } 
}

You can just write your String Extension for comparison in just a few line of code

你可以只用几行代码编写你的字符串扩展来进行比较