iOS:音频MP3文件路径

if let path = Bundle.main.path(forResource: "audio", ofType: "mp3") {
    // 文件路径为path
} else {
    // 文件不存在
}

if let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first {
    let audioURL = documentsDirectory.appendingPathComponent("audio.mp3")
    // 文件路径为audioURL.path
} else {
    // 获取文档目录失败
}

if let cacheDirectory = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first {
    let audioURL = cacheDirectory.appendingPathComponent("audio.mp3")
    // 文件路径为audioURL.path
} else {
    // 获取缓存目录失败
}