Extensions May not contain Stored properties
Can I implement this in Swift with Extensions without the need to inheritance?. I get this error Extensions May not contain Stored properties
extension UIButton
{
@IBInspectable var borderWidth : CGFloat
{
didSet{
layer.borderWidth = borderWidth
}
}
}
You can override the setter/getter so that it isn't a stored property and just forwards the set/get to the layer.
extension UIButton {
@IBInspectable var borderWidth : CGFloat {
set {
layer.borderWidth = newValue
}
get {
return layer.borderWidth
}
}
}
Extensions cannot add stored properties. From the docs (Computed Properties section):
Note
Extensions can add new computed properties, but they cannot add stored properties, or add property observers to existing properties.
If you have a need for stored properties, you should create a subclass, like so:
class CustomButton : UIButton
{
@IBInspectable var borderWidth : CGFloat
{
didSet{
layer.borderWidth = borderWidth
}
}
}
In Swift, I'm importing a static library written in Objective-C. The protocol below, in that library, has a method and a property.
@class Message;
@protocol LocalService
@property (readonly) int action;
- (Message *)getResponse:(Message *)request;
@end
Trying to have a class conform to that protocol, delivers the messages below:
1-) Type 'ShowInitialViewLocalService' does not conform to protocol 'LocalService
2-) Extensions may not contain stored properties
The code provided below, fixes this issue:
import UIKit
class ShowInitialViewLocalService: NSObject{
}
extension ShowInitialViewLocalService : LocalService {
var action: Int32 {
get { return View.InitialView.rawValue }
}
func getResponse(_ request: Message) -> Message {
let response = Response(source: request.target, target: request.source, relatedView: View.InitialView.rawValue, action: request.action, data: request.data)
return response
}
}
I hope this will help someone.