Question

我需要一些帮助来理解MPMediaQuery以及如何访问结果，以便我可以使用setQueue（带:)的查询。

以下是我为何感到困惑的一个例子。

在我的图书馆里，我有一张有3张专辑的艺术家。我的目标是按顺序查看这3张专辑：

专辑A.
- track 1
- track 2
- track 3
专辑2
- track 1
- track 2
- track 3
专辑3
- track 1
- track 2
- track 3

当我使用此查询时，相册/歌曲未按预期排序。即使没有随机播放，它们几乎会出现洗牌现象。

var qryArtists = MPMediaQuery()
qryArtists = MPMediaQuery.artists()
qryArtists.groupingType = MPMediaGrouping.albumArtist
let currLoc = qryArtists.collectionSections![indexPath.section].range.location
myMP.setQueue(with: qryArtists.collections![indexPath.row + currLoc])
for junk in qryArtists.collections![indexPath.row + currLoc].items{
    print(" collections title \(junk.albumTitle!) track \(junk.albumTrackNumber) song \(junk.title!)")
}

我得到了这些结果：

collections title Cosmic Thing track 8 song Channel Z collections title Cosmic Thing track 1 song Cosmic Thing collections title Wild Planet track 6 song Devil In My Car collections title Wild Planet track 2 song Dirty Back Road collections title Wild Planet track 4 song Give Me Back My Man collections title Cosmic Thing track 5 song June Bug collections title Wild Planet track 1 song Party Out Of Bounds collections title Wild Planet track 5 song Private Idaho collections title Wild Planet track 7 song Quiche Lorraine collections title Cosmic Thing track 6 song Roam collections title The B-52's track 15 song Rock Lobster collections title Wild Planet track 3 song Runnin' Around collections title Wild Planet track 8 song Strobe Light collections title Cosmic Thing track 9 song Topaz collections title Wild Planet track 9 song 53 Miles West Of Venus

请注意专辑/歌曲的顺序不正确

但是，如果我使用此print语句，我会得到预期的结果：

for junk in newQry.items!{
    print("items title \(junk.albumTitle!) track \(junk.albumTrackNumber) song \(junk.title!)")
}

结果：

items title The B-52's track 15 song Rock Lobster items title Cosmic Thing track 1 song Cosmic Thing items title Cosmic Thing track 5 song June Bug items title Cosmic Thing track 6 song Roam items title Cosmic Thing track 8 song Channel Z items title Cosmic Thing track 9 song Topaz items title Wild Planet track 1 song Party Out Of Bounds items title Wild Planet track 2 song Dirty Back Road items title Wild Planet track 3 song Runnin' Around items title Wild Planet track 4 song Give Me Back My Man items title Wild Planet track 5 song Private Idaho items title Wild Planet track 6 song Devil In My Car items title Wild Planet track 7 song Quiche Lorraine items title Wild Planet track 8 song Strobe Light items title Wild Planet track 9 song 53 Miles West Of Venus

另外，另一个非常奇怪的效果：如果我设置了MusicPlayer查询：

myMP.setQueue(with: newQry)

然后发出相同的＆＃39;项目＆＃39; print语句，现在结果与＆＃39;集合＆＃39;完全相同。版本！

为什么设置队列会改变查询的行为方式？

由于我不能setQueue使用newQry.items，我如何建立一个队列以预期的顺序获取相册和歌曲？

Answer 1

好的，我通过更多的研究自己解决了这个问题。这里的技巧是使用正确排序的ITEMS，并构建一个新的集合作为队列。

只需添加一行代码：

tensor = tensor > 0

然后更改setQueue函数：

let collection = MPMediaItemCollection(items: newQry.items!)

这是最终的工作代码块 - 与我上面的原始帖子OP进行比较：

myMP.setQueue(with: collection)

需要对集合和项目的MPMediaQuery结果进行很好的解释

1 个答案: