{"action":"closed","issue":{"url":"https://api.github.com/repos/Glow-Inc/GLPubSub/issues/2","labels_url":"https://api.github.com/repos/Glow-Inc/GLPubSub/issues/2/labels{/name}","comments_url":"https://api.github.com/repos/Glow-Inc/GLPubSub/issues/2/comments","events_url":"https://api.github.com/repos/Glow-Inc/GLPubSub/issues/2/events","html_url":"https://github.com/Glow-Inc/GLPubSub/issues/2","id":66834222,"number":2,"title":"为什么用 set 存储 observer","user":{"login":"callmewhy","id":6276527,"avatar_url":"https://avatars.githubusercontent.com/u/6276527?v=3","gravatar_id":"","url":"https://api.github.com/users/callmewhy","html_url":"https://github.com/callmewhy","followers_url":"https://api.github.com/users/callmewhy/followers","following_url":"https://api.github.com/users/callmewhy/following{/other_user}","gists_url":"https://api.github.com/users/callmewhy/gists{/gist_id}","starred_url":"https://api.github.com/users/callmewhy/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/callmewhy/subscriptions","organizations_url":"https://api.github.com/users/callmewhy/orgs","repos_url":"https://api.github.com/users/callmewhy/repos","events_url":"https://api.github.com/users/callmewhy/events{/privacy}","received_events_url":"https://api.github.com/users/callmewhy/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":3,"created_at":"2015-04-07T09:20:11Z","updated_at":"2015-04-08T01:52:08Z","closed_at":"2015-04-08T01:52:08Z","body":"在下面的方法中：\r\n\r\n    - (id)subscribe:(NSString *)eventName obj:(id)obj handler:(GLEventHandler)handler {\r\n\r\n使用 NSMutableDictionary 存储了事件对应的 observers， 使用 nsset 存储了observer。\r\n\r\n比较好奇的是为什么不直接用 NSMutableDictionary 而套了一层 set ？谢谢"}}