PodcastPlayer

Episode Feed Feature Specs (Homepage)

Narrative#1

As a podcast audioence
I want the app to automatically load the lastest podcast epiosde
So I can always enjoy the newest feed of the channel

Scenarios

Given the audioence has connectivity
 When the audioence requests to see the channel feed
 Then the app should display the latest feed from remote

Use cases

Load Episode Feed From Remote Use Case

Data:

• URL

Primary Course( happy path ):

1. Execute ‘func load’ and with data above.
2. System download data with URL
3. System validates downloading data
4. System creates channel feed for validate data
5. System deliver channel feed

Invalid Data( sad path ):

System delivers invalidate data error

No Connectivity( sad path ):

System delivers connectivity error

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Flowchart

Model Specs

Channel Feed

Property	Type
profileImage	URL(optional)
episodes	[Episode]

Episode

Property	Type
coverImage	URL(optional)
title	String(optional)
description	String
releaseDate	String
soundURL	URL(optional)

Example

<channel>
        <image>
            <url>https://i1.sndcdn.com/avatars-000326154119-ogb1ma-original.jpg</url>
        </image>
        <item>
            <guid isPermaLink="false">tag:soundcloud,2010:tracks/1000284829</guid>
            <title>Ep. 135 流動的資金盛宴</title>
            <pubDate>Sun, 07 Mar 2021 22:00:12 +0000</pubDate>
            <description>現代金融理論加上現代科技，解放資本，將所有人捲入投資市場。人們有更多資訊、投資對象，以及比較的對象。就像手機讓人們滑臉書欲罷不能，閒不下來；科技也讓人們追逐投資報酬率，無法接受資本「閒置」。看似更有效率的市場背後，是更大的風險。

主題文章：博弈、科技與投資自己之必要
https://bit.ly/2MSu8Qk
首月一元訂閱，即可看網站全文
bit.ly/37Yi4D4</description>
            <enclosure type="audio/mpeg" url="https://feeds.soundcloud.com/stream/1000284829-daodutech-podcast-a-liquid-feast-of-capital.mp3" length="60557439"/>
            <itunes:image href="https://i1.sndcdn.com/artworks-Z7zJRFuDjv63KCHv-5W8whA-t3000x3000.jpg"/>
        </item>

Episode Page Specs (Episode Page)

Narrative#1

As a podcast audioence
I want to look into selected episode's description
So I can learn more about the topic and project

Use cases

Display episode detail

Data:

• array of Episode
• Int

Primary Course( happy path ):

1.Load episode
2.Kingfisher load episode coverImage with URL
3.Render UI component with episode

Episode property contains valid value ( sad path ):

System delivers invalid data error

Cover image’s URL couldn’t load ( sad path ):

Kingfisher displays placeholder on UIImageView

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Transfer to player page and start to play audio

Primary Course( happy path ):

Transfer to player page

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Player

Narrative

As an audience who already peruse episode's summary
Finally decided to listen to the content
The app should be able to let me play the podcast

Use cases

Load Sound URL

Data:

• URL https://xxx.sound.mp3

Primary Course( happy path ):

1.AVPlayerItem load url, and the url is valid
2.AVPlayerItem is ready to play
3.AVPlayer play the audio

The url is invlid ( sad path ):

System doesn't play the audio

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Play Audio

Primary Course( happy path ):

1.AVPlayerItem is ready to play
2.AVPlayer play the audio

The AVPlayerItem is not ready( sad path ):

System doesn't play the audio

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Pause Audio

Primary Course( happy path ):

1. AVPlayerItem is ready to play
   
2. AVPlayer pause the audio
   

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Switch to Next/Previous Episode

Data:

• Input: [Episode], Int
• Output: Result<( Episode, URL), Error>

Primary Course( happy path ):

1. Execute ‘func loadEpisode’
   
2. PlayerModel retrieve episode and URL for Controller
   
3. Render interface with episode
   
4. AudioPlayer load sound URL
   
5. AVPlayerItem is read to play
   
6. AVPlayer start to play
   

Index out of range ( sad path ):

System delivers index out of range error

Sound URL is missing ( sad path ):

System delivers sound URL is missing error

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Manipulate episode with Slider

Data:

• Double

Default configuration for AVPlayerManager:

public final class AVPlayerManager {
    private var player:AVPlayer?
    
    private var timeObserver: Any?
        
    private var isSeekInProgress = false
    
    private var chaseTime: CMTime = .zero

Primary Course( happy path ):

1. AVPlayer currentItem's duration is not nil
   
2. Convert slider value to total second
   
3. Convert sldier value, the process is shown as below:

if let duration = player?.currentItem?.duration {
            let totalSecond = CMTimeGetSeconds(duration)
            
            let value = (sliderValue) * Float(totalSecond)
            
            let seekTime = CMTime(value: CMTimeValue(value), timescale: 1)
           }

4. Execute func stopPlayingAndSeekSmoothlyToTime(newChaseTime:)
5. Pause AVPlayer
6. Compare currentChaseTime with newChaseTime

if CMTimeCompare(newChaseTime, chaseTime) != 0 {
            chaseTime = newChaseTime
            
            if !isSeekInProgress {
                trySeekToChaseTime()
            }
        }

7. Check statement isSeekInProgress

if !isSeekInProgress {
                trySeekToChaseTime()
            }

8. Check AVPlayer currentItem's status.

if status == .unknown {
            // wait until item becomes ready
        } else if status == .readyToPlay {
            actuallySeekToTime()
        }

9. isSeekInProgress = true
10. let seekTimeInProgress = chaseTime
11. Execute AVPlayer.seekseek(to: seekTimeInProgress, toleranceBefore: .zero, toleranceAfter: .zero, completion:)
12. Execute CMTimeCompare(seekTimeInProgress, self.chaseTime)

if CMTimeCompare(seekTimeInProgress, self.chaseTime) == 0 {
                self.isSeekInProgress = false
            } else {
                self.trySeekToChaseTime()
            }

14. notify PlayerViewController to update

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Flowchart ( Play Newer/Older Episode )

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App Architecture

Home Page

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Player Page