ios開發之Swift擷取視頻截圖（本地視頻、網路視頻的縮圖）

有時我們需要在介面上顯示視頻的縮圖，這樣使用者不用點開也能大概瞭解到視頻的內容。下面分別示範如何擷取本地視頻，以及網路線上視頻的視頻截圖。

範例的效果圖如下，將擷取到的截圖（視頻開始部分）顯示在 imageView 中。

1，擷取本地視頻截圖

import UIKit
import AVFoundation
import MobileCoreServices
 
class ViewController: UIViewController {
 
    @IBOutlet weak var imageView: UIImageView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        //擷取本地視頻
        let filePath = NSBundle.mainBundle().pathForResource("hangge", ofType: "m4v")
        let videoURL = NSURL(fileURLWithPath: filePath!)
        let avAsset = AVAsset(URL: videoURL)
        
        //產生視頻截圖
        let generator = AVAssetImageGenerator(asset: avAsset)
        generator.appliesPreferredTrackTransform = true
        let time = CMTimeMakeWithSeconds(0.0,600)
        var actualTime:CMTime = CMTimeMake(0,0)
        let imageRef:CGImageRef = try! generator.copyCGImageAtTime(time, actualTime: &actualTime)
        let frameImg = UIImage(CGImage: imageRef)
        
        //顯示截圖
        self.imageView.image = frameImg
    }
 
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

2，擷取網路視頻截圖

由於網路請求比較耗時，所以我們把擷取線上視頻的相關代碼寫在非同步線程裡。

import UIKit
import AVFoundation
import MobileCoreServices
 
class ViewController: UIViewController {
    
    @IBOutlet weak var imageView: UIImageView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        
        //非同步擷取網路視頻
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0), {
            //擷取網路視頻
            let url = "http://www.hangge.com/hangge.mp4"
            let videoURL = NSURL(string: url)!
            let avAsset = AVURLAsset(URL: videoURL)
            
            //產生視頻截圖
            let generator = AVAssetImageGenerator(asset: avAsset)
            generator.appliesPreferredTrackTransform = true
            let time = CMTimeMakeWithSeconds(0.0,600)
            var actualTime:CMTime = CMTimeMake(0,0)
            let imageRef:CGImageRef = try! generator.copyCGImageAtTime(time, actualTime: &actualTime)
            let frameImg = UIImage(CGImage: imageRef)
            
            //在主線程中顯示截圖
            dispatch_async(dispatch_get_main_queue(), {
                self.imageView.image = frameImg
            })
        })
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}