Next and Previous Implementation

import UIKit
import StreamingKit

private let singletonInstance = NineInchAudio()

class NineInchAudio {
    
    class var manager: NineInchAudio {
        return singletonInstance
    }
    
    var audioPlayer:STKAudioPlayer
    
    var songsArray = [Song]()
    
    var startIndex = 0
    var artistImage = "1"
    
    var currentPlayingSongName = ""

    init() {
        self.audioPlayer = STKAudioPlayer()
    }
    
    func addSongsToPlay(songs:[Song]){
        self.songsArray.removeAll(keepCapacity: false)
        self.songsArray += songs
        println("\(self.songsArray)")
    }
    
    func damnPlayThisSong(url: String) {
        var songUrl = url
        println("\(self.songsArray)")
        
        self.audioPlayer.play(songUrl)
        
    }
    
    func startPlaying(index: Int){
        
        self.startIndex = index
        
        if self.audioPlayer.currentlyPlayingQueueItemId() != nil {
            println("Currntly Playing Item : \(self.audioPlayer.currentlyPlayingQueueItemId())")
            return
        }
        
        for var i = startIndex; i < songsArray.count; i++ {
            self.audioPlayer.queue(self.songsArray[i].songTrack)
            println("\(self.songsArray[i].songTrack)")
        }
        
    }
    
    func startPlaying(){

        if self.audioPlayer.currentlyPlayingQueueItemId() != nil {
            println("Currntly Playing Item : \(self.audioPlayer.currentlyPlayingQueueItemId())")
            return
        }
        
        for var i = startIndex; i < songsArray.count; i++ {
            self.audioPlayer.queue(self.songsArray[i].songTrack)
            println("\(self.songsArray[i].songTrack)")
        }
        
    }
    
    // Play Next Song and the rest
    func startPlayingNextSong() {
        
        startIndex = startIndex + 1
        
        for var i = startIndex; i < songsArray.count; i++ {
            self.audioPlayer.queue(self.songsArray[i].songTrack)
        }
    }
    
    // Play Previous Song and the rest
    func startPlayingPreviousSong() {
        
        if startIndex > 0 {
            startIndex = startIndex - 1
            
            for var i = startIndex; i < songsArray.count; i++ {
                self.audioPlayer.queue(self.songsArray[i].songTrack)
            }
            
        }
 
    }
    
    func stopPlaying() -> Bool {
        self.audioPlayer.stop()
        return true
    }
    
    func pausePlaying() {
        self.audioPlayer.pause()
    }
    
    func resumePlaying() {
        self.audioPlayer.resume()
    }
    
    // MARK: Helpers
    /*
    * Format the float time values like duration
    * to format with minutes and seconds
    */
    func timeFormat(value: Float) -> String {
        
        var minutes = Float(floor(Float(lroundf(value)/60)))
        var seconds = Float(lroundf(value)) - (minutes * 60)
        
        var roundedSeconds = lroundf(seconds)
        var roundedMinutes = lroundf(minutes)
        
        let numberOfDecimal = "02"
        
        var time = "\(roundedMinutes.format(numberOfDecimal)):\(roundedSeconds.format(numberOfDecimal))"
        
        return time
        
    }
    
    func setCurrentAudioTime(value: Float) {
        self.audioPlayer.seekToTime(Double(value))
    }
    
    func setCurrentAudioTime(value: Double) {
        self.audioPlayer.seekToTime(value)
    }
    
    func getCurrentAudioTime() -> NSTimeInterval {
        return self.audioPlayer.progress
    }
    
    func getAudioDuration() -> Float {
        return Float(self.audioPlayer.duration)
    }
    
    func getPlayerState() -> Int {
        
        var state: STKAudioPlayerState?
        var value = 1234567890
        
        if self.audioPlayer.state.value == STKAudioPlayerStateBuffering.value {
            println("Buffering Value : \(STKAudioPlayerStateBuffering.value)")
            state = STKAudioPlayerStateBuffering
            value = Int(STKAudioPlayerStateBuffering.value)
            
            
        } else if self.audioPlayer.state.value == STKAudioPlayerStateDisposed.value {
            println("Disposed Value : \(STKAudioPlayerStateDisposed.value)")
            state = STKAudioPlayerStateDisposed
            value = Int(STKAudioPlayerStateDisposed.value)
            
        } else if self.audioPlayer.state.value == STKAudioPlayerStateError.value {
            println("Error value : \(STKAudioPlayerStateDisposed.value)")
            state = STKAudioPlayerStateError
            value = Int(STKAudioPlayerStateError.value)
            
            
        } else if self.audioPlayer.state.value == STKAudioPlayerStatePaused.value {
            println("Paused value: \(STKAudioPlayerStatePaused.value)")
            state = STKAudioPlayerStatePaused
            value = Int(STKAudioPlayerStatePaused.value)
            
        } else if self.audioPlayer.state.value == STKAudioPlayerStatePlaying.value {
            println("Playing Value ; \(STKAudioPlayerStatePlaying.value)")
            println("Song Name : \(self.audioPlayer.currentlyPlayingQueueItemId())")
            println()
            
            for var i = 0; i < songsArray.count; i++ {
                if self.audioPlayer.currentlyPlayingQueueItemId() == self.songsArray[i].songTrack {
                    self.currentPlayingSongName = self.songsArray[i].songTitle
                }
            }
        
            state = STKAudioPlayerStatePlaying
            value = Int(STKAudioPlayerStatePlaying.value)
            
        } else if self.audioPlayer.state.value == STKAudioPlayerStateReady.value {
            println("Ready Value : \(STKAudioPlayerStateReady.value)")
            state = STKAudioPlayerStateReady
            value = Int(STKAudioPlayerStateReady.value)
            
        } else if self.audioPlayer.state.value == STKAudioPlayerStateRunning.value {
            println("Running Value : \(STKAudioPlayerStateRunning.value)")
            state = STKAudioPlayerStateRunning
            value = Int(STKAudioPlayerStateRunning.value)
            
        } else if self.audioPlayer.state.value == STKAudioPlayerStateStopped.value {
            println("Stopped Value : \(STKAudioPlayerStateStopped.value)")
            state = STKAudioPlayerStateStopped
            value = Int(STKAudioPlayerStateStopped.value)
        }
        
        println("Value -------------------------- \(value)")
        return value
    }
    
}

// Ref: http://stackoverflow.com/a/24055762
extension Int {
    func format(f: String) -> String {
        return NSString(format: "%\(f)d", self) as String
    }
}