How can I check if a string contains Chinese in Swift? - swift

Question

I want to know that how can I check if a string contains Chinese in Swift?
For example, I want to check if there's Chinese inside:
var myString = "Hi! 大家好！It's contains Chinese!"
Thanks!

Answer 1

This answer
to How to determine if a character is a Chinese character can also easily be translated from
Ruby to Swift (now updated for Swift 3):
extension String {
var containsChineseCharacters: Bool {
return self.range(of: "\\p{Han}", options: .regularExpression) != nil
}
}
if myString.containsChineseCharacters {
print("Contains Chinese")
}
In a regular expression, "\p{Han}" matches all characters with the
"Han" Unicode property, which – as I understand it – are the characters
from the CJK languages.

Answer 2

Looking at questions on how to do this in other languages (such as this accepted answer for Ruby) it looks like the common technique is to determine if each character in the string falls in the CJK range. The ruby answer could be adapted to Swift strings as extension with the following code:
extension String {
var containsChineseCharacters: Bool {
return self.unicodeScalars.contains { scalar in
let cjkRanges: [ClosedInterval<UInt32>] = [
0x4E00...0x9FFF, // main block
0x3400...0x4DBF, // extended block A
0x20000...0x2A6DF, // extended block B
0x2A700...0x2B73F, // extended block C
]
return cjkRanges.contains { $0.contains(scalar.value) }
}
}
}
// true:
"Hi! 大家好！It's contains Chinese!".containsChineseCharacters
// false:
"Hello, world!".containsChineseCharacters
The ranges may already exist in Foundation somewhere rather than manually hardcoding them.
The above is for Swift 2.0, for earlier, you will have to use the free contains function rather than the protocol extension (twice):
extension String {
var containsChineseCharacters: Bool {
return contains(self.unicodeScalars) {
// older version of compiler seems to need extra help with type inference
(scalar: UnicodeScalar)->Bool in
let cjkRanges: [ClosedInterval<UInt32>] = [
0x4E00...0x9FFF, // main block
0x3400...0x4DBF, // extended block A
0x20000...0x2A6DF, // extended block B
0x2A700...0x2B73F, // extended block C
]
return contains(cjkRanges) { $0.contains(scalar.value) }
}
}
}

Answer 3

The accepted answer only find if string contains Chinese character, i created one suit for my own case:
enum ChineseRange {
case notFound, contain, all
}
extension String {
var findChineseCharacters: ChineseRange {
guard let a = self.range(of: "\\p{Han}*\\p{Han}", options: .regularExpression) else {
return .notFound
}
var result: ChineseRange
switch a {
case nil:
result = .notFound
case self.startIndex..<self.endIndex:
result = .all
default:
result = .contain
}
return result
}
}
if "你好".findChineseCharacters == .all {
print("All Chinese")
}
if "Chinese".findChineseCharacters == .notFound {
print("Not found Chinese")
}
if "Chinese你好".findChineseCharacters == .contain {
print("Contains Chinese")
}
gist here: https://gist.github.com/williamhqs/6899691b5a26272550578601bee17f1a

Answer 4

Try this in Swift 2:
var myString = "Hi! 大家好！It's contains Chinese!"
var a = false
for c in myString.characters {
let cs = String(c)
a = a || (cs != cs.stringByApplyingTransform(NSStringTransformMandarinToLatin, reverse: false))
}
print("\(myString) contains Chinese characters = \(a)")

Answer 5

I have created a Swift 3 String extension for checking how much Chinese characters a String contains. Similar to the code by Airspeed Velocity but more comprehensive. Checking various Unicode ranges to see whether a character is Chinese. See Chinese character ranges listed in the tables under section 18.1 in the Unicode standard specification: http://www.unicode.org/versions/Unicode9.0.0/ch18.pdf
The String extension can be found on GitHub: https://github.com/niklasberglund/String-chinese.swift
Usage example:
let myString = "Hi! 大家好！It contains Chinese!"
let chinesePercentage = myString.chinesePercentage()
let chineseCharacterCount = myString.chineseCharactersCount()
print("String contains \(chinesePercentage) percent Chinese. That's \(chineseCharacterCount) characters.")