[WWDC19] Data Flow Through SwiftUI(03) Save Image Image gallery: Cannot Use Mutating Member On Immutable Value 'self' Is Immutable
![[WWDC19] Data Flow Through SwiftUI(03)](https://i2.wp.com/velog.velcdn.com/images/marisol/post/0a46b53f-ccf0-49d8-84a6-4f2801eb5236/image.png)
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![Array Immutable value of type '[String]' only has mutating member](https://i.ytimg.com/vi/epbXme7GjfM/maxresdefault.jpg "Array Immutable value of type '[String]' only has mutating member")
