如何将一个结构转换为另一个具有相同变量 Swift (iOS) 的结构？

Question

I need help with converting one object to another. Might have searched 10-20 website didn't find any good answer.

public struct UniversityJoinChatViewModel {
    public let id: Int?
    public let name: String?
    public init(nameOfModel model : UniversityGroupChatItem?) {
          self.id = model?.id;
          self.name = model?.name;
    }
}
public struct UniversityGroupChatItem: Codable {
    public let id: Int?
    public let name: String?
    public init(id: Int?, name: String?) {
        self.id = id
        self.name = name
    }
}

I did this:

let say I have value UniversityGroupChatItem in variable universityGroupChatItem and my universityGroupChatItem contains is not nil and contains value. I tried this it did not work.

universityJoinChatViewModel = (universityGroupChatItem) as! UniversityJoinChatViewModel

The app crashed.

Then I tried:

map and compactmap

None worked.

I am not getting how to convert UniversityGroupChatItem struct to UniversityJoinChatViewModel struct.

I do not understand how to convert one struct to another struct both has same number name variables.

Answer 1

You can't force cast one object into another (no matter struct, class, enum ect.) even if they are fully the same inside

You need to implement inits where one object takes fields from another one.

map is function to sequences, if You have only 1 object just init it with another one

Examples:

  public struct UniversityJoinChatViewModel {
        public let id: Int?
        public let name: String?
        public init(nameOfModel model : UniversityGroupChatItem?) {
              self.id = model?.id;
              self.name = model?.name;
        }
    }
    public struct UniversityGroupChatItem: Codable {
        public let id: Int?
        public let name: String?
        public init(id: Int?, name: String?) {
            self.id = id
            self.name = name
        }
    }
    
    let universityGroupChatItem = UniversityGroupChatItem(id: 0, name: "name")
    let universityJoinChatViewModel = UniversityJoinChatViewModel(nameOfModel: universityGroupChatItem)
    let groupArray = Array(repeating: universityGroupChatItem, count: 10)
    let joinArray = groupArray.map(UniversityJoinChatViewModel.init(nameOfModel:))

Answer 2

In your case, you already have the constructor that can help you to achieve what you want, so instead of trying to cast the object, create a new one:

universityJoinChatViewModel = UniversityJoinChatViewModel(nameOfModel: universityGroupChatItem)