Errors

Errors

Property not found

Property not found on object of swift class but its internal properties aren't exposed to objective-c header / bridging interface so you need to add @objc property wrapper on those variables or functions to access them.

error: property 'propertyName' not found on object of type 'SomeClass *'

public class SomeClass: NSObject {
    @objc public var propertyName: String?
    var strID: String?
}

@objc attribute cannot be applied

'@objc' attribute cannot be applied to this declaration

This error could appear when the underlying implementation is struct or something which is not able to be represented in Objective C bridging options.
Swift has structs but objectiveC doesn't support it directly.

A Warm Welcome to Structs and Value Types from Objc.io post
swift-classes-vs-structs post

Support Struct in Objective C

You can wrap it as a generic value in Swift class and have the generic value as Struct

public class Box<T> {
    let unbox: T
    init(_ value: T) {
        self.unbox = value
    } }

SO | how-to-pass-a-swift-struct-as-a-parameter-to-an-objective-c-method

Things not supported by @Objc

You’ll have access to anything within a class or protocol that’s marked with the @objc attribute as long as it’s compatible with Objective-C. This excludes Swift-only features such as those listed here:

• Generics
• Tuples
• Enumerations defined in Swift
• Structures defined in Swift
• Top-level functions defined in Swift
• Global variables defined in Swift
• Typealiases defined in Swift
• Swift-style variadics
• Nested types
• Curried functions

SwiftObjcCocoa.pdf