How do you inspect an Optional-String's length?

Question

class PersonEntry: NSObject {
  var firstName: String?
  var lastName: String?
}

//This errors
if (self.person.firstName?.isEmpty) {
          println("Empty")
}

//Compiler auto-correction is this
if ((self.model.firstName?.isEmpty) != nil) {
          println("Empty")
}

I understand that optional chaining returns an optional type. So I suppose my question is, how do you unwrap an optional string, to inspect it's length, without risking a crash ?

Similar question (with two different solutions) here: [Evaluate Bool property of optional object in if statement](http://stackoverflow.com/questions/26910229/evaluate-bool-property-of-optional-object-in-if-statement). — Martin R, Mar 04 '15 at 21:03

Antonio · Accepted Answer · 2015-03-05T11:38:09.753

10

I presume that if the property is nil then you want to consider it empty - in that case you can use the nil coalescing operator in combination with the first version of the if statement:

if self.person.firstName?.isEmpty ?? true {
          println("Empty")
}

If firstName is nil, the expression evaluates to the right side of the coalescing operator, true - otherwise it evaluates to the value of the isEmpty property.

References:

Nil Coalescing Operator

Optional Chaining

edited Mar 05 '15 at 11:38

answered Mar 04 '15 at 20:51

Antonio

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thanks Antonio. do you know a good link for reading up on this particular syntax. i would like to read around it. – Mar 05 '15 at 11:32
1

@robdashnash: added links to the answer – Antonio Mar 05 '15 at 11:38

score 0 · Answer 2 · answered May 24 '15 at 06:22

0

Another trick.

var str: String?
str = "Hello, playground"

println(count(str ?? ""))

answered May 24 '15 at 06:22

iwat

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How do you inspect an Optional-String's length?

2 Answers2