Why Choose Struct Over Class?

Question

Playing around with Swift, coming from a Java background, why would you want to choose a Struct instead of a Class? Seems like they are the same thing, with a Struct offeri

Answer 1

Answering the question from the perspective of value types vs reference types, from this Apple blog post it would appear very simple:

Use a value type [e.g. struct, enum] when:

• Comparing instance data with == makes sense
• You want copies to have independent state
• The data will be used in code across multiple threads

Use a reference type [e.g. class] when:

• Comparing instance identity with === makes sense
• You want to create shared, mutable state

As mentioned in that article, a class with no writeable properties will behave identically with a struct, with (I will add) one caveat: structs are best for thread-safe models -- an increasingly imminent requirement in modern app architecture.