Swift 协议的静态要求是什么？

Question

在 Swift 中尝试使用 ObjC 中的代码时，我遇到了以下 Swift 错误：

'myClass & myProtocol' cannot be used as a type conforming to protocol 'myProtocol' because 'myProtocol' has static requirements

代码大致如下：

@interface FooGenericContainer <T : MyClass < MyProtocol > *> : MyClass

func asFoo() -> FooGenericContainer<MyClass & MyProtocol> { /// <-- error here
  ....
}

@protocol MyProtocol <NSObject, NSCopying, NSMutableCopying, AnotherProtocol>
@end

...

@protocol AnotherProtocol <NSObject, NSCopying, NSMutableCopying>

+ (NSDictionary *)method1;

@optional

+ (NSDictionary *)method2;

@end

什么是协议的“静态要求”，这些是它具有的类方法吗？

我该如何克服这个错误？

我可以返回FooGenericContainer 而不指定泛型类型吗？

Answer 1

我通过在 MyClass 定义中添加 <MyProtocol> 来解决错误

这是我使用的代码

// copied from a header that's included in the bridging header in OBJC

@protocol AnotherProtocol <NSObject, NSCopying, NSMutableCopying>
+ (NSDictionary *)method1;
@optional
+ (NSDictionary *)method2;
@end

@protocol MyProtocol <NSObject, NSCopying, NSMutableCopying, AnotherProtocol>
@end

// ? Note: if I didn't include '<MyProtocol>' it would give me the static requirement error
@interface MyClass <MyProtocol>
@end

@interface FooGenericContainer <T: MyClass<MyProtocol> *> : MyClass
@end

然后迅速

// I made this optional just to get it to compile
func asFoo() -> FooGenericContainer<MyClass & MyProtocol>? {
    return nil
}