Inheritance from non-protocol type 'PFObject'

I am getting this error Inheritance from non-protocol type 'PFObject' on Xcode with Swift while trying to create a Model, here is the code of the model:

import Foundation
import ParseSwift
import Parse
import SwiftUI

struct Category: ParseObject, PFObject {

    // Required properties from ParseObject protocol
    var originalData: Data?
    var objectId: String?
    var createdAt: Date?
    var updatedAt: Date?
    var ACL: ParseACL?

    // Custom fields for the contact's information
    var name: String = ""
    var cover: String = ""
    var color: String = ""
    var createdBy: String = ""
}

extension Category {
    init(name: String, cover: String, color: String, createdBy: String) {
        self.name = name
        self.cover = cover
        self.color = color
        self.createdBy = createdBy
    }
}

What am I doing wrong?

It looks like you are trying to use Parse-Swift and the Parse Objective-C SDK at the same time which you shouldn't be doing. Your ParseObject is setup using Parse-Swift so assuming that's what you want to use, remove, import Parse and your Parse Object should look like:

import Foundation
import ParseSwift
import SwiftUI

struct Category: ParseObject {

    // Required properties from ParseObject protocol
    var originalData: Data?
    var objectId: String?
    var createdAt: Date?
    var updatedAt: Date?
    var ACL: ParseACL?

    // All Custom fields should be optional
    var name: String?
    var cover: String?
    var color: String?
    var createdBy: String?
}

extension Category {
    init(name: String, cover: String, color: String, createdBy: String) {
        self.name = name
        self.cover = cover
        self.color = color
        self.createdBy = createdBy
    }
}

Remove the Parse dependency completely from your project as Parse-Swift doesn't use or need it at all. The playgrounds in Parse-Swift show how to use the SDK correctly along with any imports that are needed to use the SDK.