用到的第三方庫:
Alamofire 用于網絡請求和視頻下載
MobilePlayer 用于播放在線視頻

創建Movie類:

import Foundation
import Alamofire

class Movie {
    
    private var url: NSURL //網絡路徑 如果本地路徑存在則是本地路徑
    
    init (url: NSURL) {
        
        self.url = url
    }

    //獲取播放路徑
    func getUrl() -> NSURL {
        
        if isExist() {
            
            let url = NSURL(fileURLWithPath: getFilePath())
            
            return url
        }
        
        return self.url
    }
    
    //通知下載 如果已經存在 不下載
    func postDownload() {
        
        if isExist() {
            
            return
        }
        
        let destination = Alamofire.Request.suggestedDownloadDestination()
 
        Alamofire.download(.GET, url, destination: destination).response { _, _, _, error in
            
            if let error = error {
                
                print("Failed with error: \(error)")
                
            } else {
                
                print("Downloaded file successfully")
            
            }
        }
        
    }
    
    //是否已經下載
    private func isExist() -> Bool{
        
        let fileManager = NSFileManager.defaultManager()
        
        let filePath = getFilePath()
        
        print(filePath)
        
        let exist = fileManager.fileExistsAtPath(filePath)
        
        return exist
    }
    
    //通過文件名稱 獲取文件路徑
    private func getFilePath() -> String {
        
        let filePath = NSHomeDirectory() + "/Documents/" + getFileName()
        
        return filePath
    }
    
    //通過url 獲取文件名稱
    private func getFileName() -> String {
        
        let array = self.url.URLString.componentsSeparatedByString("/")
        
        return array.last!
    }
    
}

創建Movie對象:

let string = "視頻路徑"
        
let url = NSURL(string: string)!
        
let movie = Movie(url: url)
        
movie.postDownload() //下載

play(movie)//播放

播放方法:

import MobilePlayer

func play(movie: Movie) {
        
    let url = movie.getUrl()
        
    let playerVC = MobilePlayerViewController(contentURL: url)
        
    playerVC.activityItems = [url]
        
    presentMoviePlayerViewControllerAnimated(playerVC)
}

一邊播放一遍下載，下載成功后會播放本地路徑的視頻。

清除所有緩存:

//清除所有緩存
func cleanAllCache() {
    
    let fileManager = NSFileManager.defaultManager()
        
    let myDirectory = NSHomeDirectory() + "/Documents"
        
    let fileArray:[AnyObject]? = fileManager.subpathsAtPath(myDirectory)
        
    for fn in fileArray!{
            
        try! fileManager.removeItemAtPath(myDirectory + "/\(fn)")
    }
        
}

這里是用的是Alamofire設置的下載路徑，注意刪除的路徑要和下載的路徑一致。

//獲取所有緩存大小
    func getAllCacheSize() -> String {
        
        let fileManager = NSFileManager.defaultManager()
        
        let myDirectory = NSHomeDirectory() + "/Documents"
        
        let fileArray:[AnyObject]? = fileManager.subpathsAtPath(myDirectory)
        
        var allSize = 0.0
        
        for fn in fileArray!{
            
            let attr = try! fileManager.attributesOfItemAtPath(myDirectory + "/\(fn)")
            
            let size = (attr["NSFileSize"] as! Double) / 1000000 //單位為 M
            
            allSize += size
        }
        
        return String(format: "%.1f", allSize) //保留小數點后一位

    }