Unexpected ‘@’ in program. 直接在协议文件h.里面实现 报警告 求解答

@protocol Forkable

@optional
- (void)fork;

@required
- (NSString *)github;
- (void)jzj;
@end
// Protocol Extension
@defs(Forkable)
- (void)fork {
NSLog(@"Forkable protocol extension: I'm forking (%@).", self.github);
}
- (void)jzj {

NSLog(@"jzj");
}
- (NSString *)github {
return @"This is a required method, concrete class must override me.";
}
@end