swift - trimmingCharacters not work on iOS 10.3 Xcode8.3

Question

Please help me, I use Xcode 8.3(swift 3.1), the function trimmingCharacters not work. My code as below:

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if var searchStr = textField.text{
       let _searchStr = searchStr.trimmingCharacters(in: .whitespaces)
       print("After trimming:(_searchStr)")
   }
}

The input in textfield is 409 hu?nh and the print result is 409 hu?nh not as expected: 409hu?nh .

Answer 1

From the documentation:

A new string made by removing from both ends of the receiver characters contained in set.

It does not remove characters within the string.

You can replace whitespaces – corresponding to the .whitespaces character set – in the string with regular expression:

let _searchStr = searchStr.replacingOccurrences(of: "\s", with: "", options: .regularExpression)