What’s the difference between == and ===?
Swift gives us two equality operators, == and ===, that do slightly different things. You will almost certainly need to use both of them so it’s worth taking the time to learn them.
First, == is the equality operator, which tests that two things are equal for whatever definition of “equal” those things use. For example, 5 == 5 is true because there == means an integer comparison, and the same is true for other built-in value types such as strings, booleans, and doubles.
Things get more complicated when == is used with a struct you built, because by default they cannot be compared – you need to make them conform to the Equatable protocol.
In comparison, === is the identity operator, which checks whether two instances of a class point to the same memory. This is different from equality, because two objects that where created independently using the same values will be considered equal using == but not === because they are different objects.
The === operator is available only when using classes because structs are designed so they are always uniquely referenced.
Available from iOS 8.0
Did this solution work for you? Please pass it on!
Other people are reading…
- What are protocol extensions?
- What are implicitly unwrapped optionals?
- What does the AppDelegate class do?
- How to convert a string to a double
- How to find the minimum of three numbers
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
