ios 扩展可能不包含存储属性
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Extensions May not contain Stored properties
提问by Mohamed DiaaEldin
Can I implement this in Swift with Extensions without the need to inheritance?. I get this error Extensions May not contain Stored properties
我可以使用扩展在 Swift 中实现它而不需要继承吗？。我收到此错误扩展可能不包含存储的属性
extension UIButton
{
@IBInspectable var borderWidth : CGFloat
{
didSet{
layer.borderWidth = borderWidth
}
}
}
回答by dan
You can override the setter/getter so that it isn't a stored property and just forwards the set/get to the layer.
您可以覆盖 setter/getter，使其不是存储属性，而只是将 set/get 转发到图层。
extension UIButton {
@IBInspectable var borderWidth : CGFloat {
set {
layer.borderWidth = newValue
}
get {
return layer.borderWidth
}
}
}
回答by Alexander
Extensions cannot add stored properties. From the docs(Computed Properties section):
扩展不能添加存储的属性。从文档（计算属性部分）：
Note
Extensions can add new computed properties, but they cannot add stored properties, or add property observers to existing properties.
笔记
扩展可以添加新的计算属性，但它们不能添加存储的属性，或向现有属性添加属性观察者。
If you have a need for stored properties, you should create a subclass, like so:
如果您需要存储属性，您应该创建一个子类，如下所示：
class CustomButton : UIButton
{
@IBInspectable var borderWidth : CGFloat
{
didSet{
layer.borderWidth = borderWidth
}
}
}
回答by Emre Gürses
In Swift, I'm importing a static library written in Objective-C. The protocol below, in that library, has a method and a property.
在 Swift 中，我导入了一个用 Objective-C 编写的静态库。下面的协议，在那个库中，有一个方法和一个属性。
@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:
试图让一个类符合该协议，传递以下消息：
1-) Type 'ShowInitialViewLocalService' does not conform to protocol 'LocalService
2-) Extensions may not contain stored properties
1-) 类型“ShowInitialViewLocalService”不符合协议“LocalService”
2-) 扩展可能不包含存储的属性
The code provided below, fixes this issue:
下面提供的代码解决了这个问题：
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.
我希望这会帮助某人。
