swift - 无法迭代 SPTPlaylistList 项目

Question

我正在尝试访问 Spotify 用户的所有播放列表

 let request2: URLRequest = try! SPTPlaylistList.createRequestForGettingPlaylists(forUser: self.username, withAccessToken: accessToken)
    print(request2)
    SPTRequest.sharedHandler().perform(request2) { (error, response, data) in
        if error == nil {
            print(response)
            let playlists = try! SPTPlaylistList(from: data, with: response)
}else{
            print(error)
        }
    }

如果我打印“播放列表”，我就可以看到播放列表

some([<SPTPartialPlaylist: 0x10aa854d0>: john mayer [2 tracks] (spotify:user:virajdeshpande88:playlist:3BLBrqb3CURu5KFPqdYqd1), <SPTPartialPlaylist: 0x10aa922a0>: beatles [2 tracks] (spotify:user:virajdeshpande88:playlist:2t6z8KEhZGzY7Tqvy8QoW4)])

但我无法单独访问播放列表或迭代 playlists.items。如果我执行以下操作:

print (playlists.items[0])

我得到“在解包可选值时意外发现 nil”。

更新:我尝试使用 playlistsForUser:withAccessToken:callback: 现在我可以访问所有用户的播放列表。但只有当以下代码块位于我上面发布的代码段的 if {} block 内时，它似乎才起作用。如果这个 block 单独放置，我会再次收到 nil 值错误。

    SPTPlaylistList.playlists(forUser: self.username, withAccessToken: accessToken, callback: {(error, playlist_list)  in
    if error == nil {
        let list = playlist_list as! SPTPlaylistList
        print(list.items[0])
        print(list.items[1])
        let playlist = list.items[0] as! SPTPartialPlaylist
        print(playlist.name)
    }else{
        print("latest error")
       }
})

Answer 1

您应该避免使用强制解包!。

    if let request2: URLRequest = try? SPTPlaylistList.createRequestForGettingPlaylists(forUser: self.username, withAccessToken: accessToken){
        print(request2)
        SPTRequest.sharedHandler().perform(request2) { (error, response, data) in
            if error == nil {
                print(response)
                if let playlists = try? SPTPlaylistList(from: data, with: response) {
                    playlists.forEach{ playlist in
                        print(playlist)
                        // do thing with your each playlist
                    }
                }
            }else{
                print(error)
            }
        }
    }