如何使用swift循环遍历目录中的多个（音频/ mp3）文件？ - Swift，iOS8 Soundboard AVPlayer

Question

I am trying to create a soundboard using Swift to fiddle around and learn about swift/iOS8.

This is what I have done in my tableViewController as of now:

var soundPath = NSBundle.mainBundle().pathForResource("RandomSound", ofType: "m4a")
var soundURL = NSURL.fileURLWithPath(soundPath!)        
self.audioPlayer = AVAudioPlayer(contentsOfURL: soundURL, error: nil)
self.audioPlayer.play()

This works to play the sound as expected. Now in order to have a few more sounds and display them in tableView, I created an array of Sound class which looks like this:

class Sound {
    var name: [String]
    var fileURL = NSURL()
    // more fields as required
}

and then using it like this:

var sounds: [Sound] = []
sounds.name = "RandomSound"
sounds.fileURL = soundURL!

However, I want something to make it to scale better . Lets say I have a bunch of mp3 files in one folder (for example 100).

In this case I would like some mechanism, with which, I can simply point the directory and/or filetype and then the remaining heavy lifting like going through each file in the directory and finding the name/artist/and other information would be extracted from mp3 file ID3 tags (or something similar).

If not all details, at least populating the name/URL field and looping over all files in a directory should be possible to automate , but I'm unable to understand what I should be looking at to achieve this.

EDIT

This part allows me scan all files in a directory of a given filetype(s). In my case I am looking for mp3. This is what I've come up with:

soundArray: [soundElement] = []
let fileManager = NSFileManager.defaultManager()
let directoryPath = "/path/to/directory/containing/my/sound/files"
let enumerator:NSDirectoryEnumerator = fileManager.enumeratorAtPath(directoryPath)!
while let element = enumerator.nextObject() as? String {
    if element.hasSuffix("mp3") { // checks the extension
        // DO my sound path stuff here
        //println(element)
        let soundURL = NSURL.fileURLWithPath(directoryPath + element)       

        //Of course I'll not be playing them directly here, (I don't see why) but if I needed to ...
        //self.audioPlayer = AVAudioPlayer(contentsOfURL: soundURL, error: nil)
        //self.audioPlayer.play()
        //Instead it just makes sense to populate some array/dict containing all the sounfURLs
        soundElement.name = String(element)
        soundElement.fileURL = soundURL
        self.soundArray.append(soundElement)

    }
}

class soundElement {
    var name = " "
    var fileURL = NSURL()
}

I am still not clear on how to get ID3 information from mp3 files in swift. I have referred the AVAsset information at https://developer.apple.com/library/ios/documentation/AVFoundation/Reference/AVAsset_Class/index.html#//apple_ref/occ/cl/AVAsset but it is not clear how to use it yet.

Answer 1

I looked at the AVAsset ( https://developer.apple.com/reference/avfoundation/avasset#//apple_ref/occ/cl/AVAsset ) docs and saw that there is a metadata property on it ( https://developer.apple.com/reference/avfoundation/avasset/1386884-metadata ).

It is an array of AVMetadataItems ( https://developer.apple.com/reference/avfoundation/avmetadataitem ) so you could check the items if they contain the metadata you are looking for (Keys are usually something like AVMetadataiTunesMetadataKeySongName in the key space AVMetadataKeySpaceiTunes or AVMetadataID3MetadataKeyAlbumTitle in the AVMetadataKeySpaceID3 .

If you want an easier solution, you could check out the ID3Edit library from this guy: https://github.com/philiphardy/ID3Edit

I'd try the following:

• Load your songs as AVAsset
• Iterate over the metadata array of each song
• Print out the keys and values of the items to identify the ones you are interested in

Once you are familiar with the structure of the metadata, you can start retrieving the ones you want.

Hope this helps