如何轉換++或 - 在Swift 3中？

Question

我有以下代碼我想轉換爲Swift 3，並得到這個奇怪的錯誤「無法將類型Bool的值轉換爲預期的參數類型Int」。當我擺脫「++」時，問題就出現了。我也鏈接到我想完全轉換的堆棧溢出問題。謝謝！下面是前面的代碼，我試圖轉換爲代碼：

前面的代碼

func previousTrack() { 
if currentTrack-- < 0 { 
    currentTrack = (playerItems.count - 1) < 0 ? 0 : (playerItems.count - 1) 
} else { 
    currentTrack-- 
} 

playTrack() 

}

變換代碼

@IBAction func didTapPreviousButton(_ sender: UIButton) { 
    if currentTrack += 1 < 0 { // Issue occurs here 
     currentTrack = (urlPlayerItems.count - 1) < 0 ? 0 : (urlPlayerItems.count - 1) 
    } else { 
     currentTrack -= 1 
    } 

    playTrack() 

} 

Original question I want to convert to Swift 3

編輯：

@IBAction func didTapPreviousButton(_ sender: UIButton) { 
    if (currentTrack - 1) <= 0 { 
     currentTrack = (urlPlayerItems.count - 1) < 0 ? 0 : (urlPlayerItems.count - 1) 
    } else { 
     currentTrack -= 1 
    } 

    playTrack() 

} 



@IBAction func didTapNextButton(_ sender: UIButton) { 
    if (currentTrack + 1) >= urlPlayerItems.count { 
     currentTrack = 0 
    } else { 
     currentTrack += 1 
    } 

    playTrack() 
} 

Answer 1

你想恕我直言

@IBAction func didTapPreviousButton(_ sender: UIButton) { 
    currentTrack -= 1 
    if currentTrack < 0 { 
     currentTrack = (urlPlayerItems.count - 1) < 0 ? 0 : (urlPlayerItems.count - 1) 
    } 

    playTrack() 
} 

正確更換字尾的是什麼，你把它（沒用）

@IBAction func didTapPreviousButton(_ sender: UIButton) { 
    if currentTrack < 0 { 
     currentTrack -= 1 
     currentTrack = (urlPlayerItems.count - 1) < 0 ? 0 : (urlPlayerItems.count - 1) 
    } 

    playTrack() 
}