objective-c - 在 Swift 中实现 Objective-C 协议(protocol)

Question

我有一个在 Objective-C 中定义的协议(protocol)，例如:

@protocol MyProtocol <NSObject>
- (void)doStuffWithDictionary:(NSDictionary*)dict 
                    andString:(NSString*)str1
            andOptionalString:(NSString*)str2
             andOptionalArray:(NSArray*)arr
                     callback:(void (^)(id result))onSuccess;
@end

...我正在尝试在 Swift 中定义一个实现此协议(protocol)的类，例如:

class MyImpl : Operation, MyProtocol {
    func doStuff(withDictionary dict: [AnyHashable : Any]!, 
                      andString str1: String!, 
              andOptionalString str2: String? = nil, 
                andOptionalArray arr: NSArray? = nil, 
                  callback onSuccess: ((Any?) -> Void)! {
        ...
    }
}

但是，我遇到了如下构建错误:

Type 'MyImpl' does not conform to protocol 'MyProtocol'
note: candidate has non-matching type '([AnyHashable : Any]!, String!, String?, NSArray?, ((Any?) -> Void)!'
    func doStuff(withDictionary dict: [AnyHashable : Any]!, andString str1: String!, andOptionalString str2: String? = nil, andOptionalArray arr: NSArray? = nil, callback onSuccess: ((Any?) -> Void)!

它似乎对 andOptionalArray arr: NSArray 感到不安？ = 无 参数。此处使用的正确语法是什么？

Answer 1

我把你的协议(protocol)放在一个项目中并在<ProjectName>-Bridging-Header.h中导入它, 并且自动完成建议使用以下语法:

public func doStuff(with dict: [AnyHashable : Any],
               andString str1: String,
       andOptionalString str2: String,
         andOptionalArray arr: [Any],
           callback onSuccess: @escaping (Any) -> Void) {
}

如果你想要 String和 [Any]要作为可选项导入，您需要将它们标记为 nullable在 Objective-C 中:

@protocol MyProtocol <NSObject>
- (void)doStuffWithDictionary:(NSDictionary*)dict
                    andString:(NSString*)str1
            andOptionalString:(nullable NSString*)str2
             andOptionalArray:(nullable NSArray*)arr
                     callback:(void (^)(id result))onSuccess;
@end

---

正如@MartinR 在评论中建议的那样:

Go to the header file where the protocol is defined, and choose "Generated Interface" from the "Related Items" popup in the top-left corner. That will show you the exact Swift method signature that you have to implement.

这也适用，并为不同版本的 Swift 提供不同的接口(interface)。