无法将返回值与字符串进行比较

Question

I'm trying to return a value (string) from php to IOS application:

echo "1";

This is the swift code:

let returnedData = NSString(data: unwrappedData, encoding: String.Encoding.utf8.rawValue) as! String
print(returnedData)
if returnedData == "1" {
     ... something
}

The print function shows the correct value (that is, 1). But the check fails.

Answer 1

String(...) gives me Optional("1\\n\\n")

That indicates that the output is followed by two newline characters, as in this example:

let data = Data(bytes: [0x31, 0x0a, 0x0a])
if let string = String(data: data, encoding: .utf8) {
    print(string) // 1
    print(string.debugDescription) // "1\n\n"
    print(string == "1") // false
}

debugDescription is a very useful method to detect “invisible” string characters.

The solution is (compare Does swift have a trim method on String? ):

let trimmed = string.trimmingCharacters(in: .whitespacesAndNewlines)
print(trimmed == "1") // true