> For the complete documentation index, see [llms.txt](https://frost.gitbook.io/iosbook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://frost.gitbook.io/iosbook/ios/ios-book/ios-class-vs-struct.md).

# \[iOS] Class vs Struct

(1) Class 是reference type

      Struct是value type

(2) Class 可以被繼承

      Struct無法被繼承

(3) Struct 有 memberwise initializer

      

```swift
let structA = StructA()

structA.width = 500 // 會造成錯誤, struct為let就不能改參數值

///////////////////////////////
let classA = ClassA()

classA.width = 500  // ok
```