Question

这个Objective-C协议曾经在Swift 1.1中工作，但现在Swift 1.2中存在错误。

Objective-C协议剥离了一个有问题的属性：

@protocol ISomePlugin <NSObject>
@property (readonly, getter=getObjects) NSArray * objects;
@end


class SomePlugin: NSObject, ISomePlugin {
    var objects: [AnyObject]! = nil
    func getObjects() -> [AnyObject]! {
        objects = ["Hello", "World"];
        return objects;
    }
}

这是Swift 1.2错误：

Plugin.swift:4:1: error: type 'SomePlugin' does not conform to protocol 'ISomePlugin'
class SomePlugin: NSObject, ISomePlugin {
^
__ObjC.ISomePlugin:2:13: note: protocol requires property 'objects' with type '[AnyObject]!'
  @objc var objects: [AnyObject]! { get }
            ^
Plugin.swift:6:9: note: Objective-C method 'objects' provided by getter for 'objects' does not match the requirement's selector ('getObjects')
    var objects: [AnyObject]! = nil
        ^

如果我将协议（我不能真正做到，因为它来自第三方）更改为以下内容，则代码编译正常。

// Plugin workaround
@protocol ISomePlugin <NSObject>
@property (readonly) NSArray * objects;
- (NSArray *) getObjects;
@end

提前致谢。

Answer 1

您可以实施

@property (readonly, getter=getObjects) NSArray * objects;

作为具有@objc属性的只读计算属性指定Objective-C名称。如果需要存储属性作为后备存储那么你必须单独定义它。例如：

class SomePlugin: NSObject, ISomePlugin {

    private var _objects: [AnyObject]! = nil

    var objects: [AnyObject]!  {
        @objc(getObjects) get {
            _objects = ["Hello", "World"];
            return _objects;
        }
    }
}

使用getter在Objective-C协议上出现Swift 1.2错误

1 个答案: