【swift】BlockOperation和GCD实用代码块详解手机开发

//BlockOperation 
 
// 
//  ViewController.swift 
  
 
import UIKit 
 
class ViewController: UIViewController { 
 
    @IBOutlet weak var image1: UIImageView! 
    @IBOutlet weak var image2: UIImageView! 
    @IBOutlet weak var image3: UIImageView! 
    @IBOutlet weak var image4: UIImageView! 
     
    let imageUrls = [ 
        "https://dn-boxueio.qbox.me/image1-big.jpg", 
        "https://dn-boxueio.qbox.me/image2-big.jpg", 
        "https://dn-boxueio.qbox.me/image3-big.jpg", 
        "https://dn-boxueio.qbox.me/image4-big.jpg" 
    ] 
     
    override func viewDidLoad() { 
        super.viewDidLoad() 
      //  present(<#T##viewControllerToPresent: UIViewController##UIViewController#>, animated: <#T##Bool#>, completion: nil) 
        // Do any additional setup after loading the view, typically from a nib. 
    } 
 
    override func didReceiveMemoryWarning() { 
        super.didReceiveMemoryWarning() 
        // Dispose of any resources that can be recreated. 
    } 
 
    @IBAction func clearDownload(_ sender: UIButton) { 
         
      //  self.image1.image=UIImage(named: <#T##String#>) 
         
        self.image1.image = nil 
        self.image2.image = nil 
        self.image3.image = nil 
        self.image4.image = nil 
         
        URLCache.shared.removeAllCachedResponses() 
    } 
 
    let queue = OperationQueue() 
     
    @IBAction func cancelDownload(_ sender: AnyObject) { 
        self.queue.cancelAllOperations() 
    } 
     
    @IBAction func downloadImages(_ sender: UIButton) { 
        
         
//        queue.addOperation({ 
//             
//             
//            let img1 = Downloader.downloadImageWithURL(self.imageUrls[0]) 
//             
//            OperationQueue.main.addOperation({ 
//                self.image1.image = img1 
//                self.image1.clipsToBounds = true 
//            }) 
//        }) 
//         
//         
        let op1 = BlockOperation(block: { 
            let img1 = Downloader.downloadImageWithURL(self.imageUrls[0]) 
             
            OperationQueue.main.addOperation({ 
                self.image1.image = img1 
                self.image1.clipsToBounds = true 
            }) 
        }) 
        op1.completionBlock = { print("image1 downloaded") } 
         
        let op2 = BlockOperation(block: { 
            let img2 = Downloader.downloadImageWithURL(self.imageUrls[1]) 
             
            OperationQueue.main.addOperation({ 
                self.image2.image = img2 
                self.image2.clipsToBounds = true 
            }) 
        }) 
        op2.completionBlock = { print("image2 downloaded") } 
         
         
         
        let op3 = BlockOperation(block: { 
            let img3 = Downloader.downloadImageWithURL(self.imageUrls[2]) 
             
            OperationQueue.main.addOperation({ 
                self.image3.image = img3 
                self.image3.clipsToBounds = true 
            }) 
        }) 
        op3.completionBlock = { print("image3 downloaded") } 
         
         
         
        let op4 = BlockOperation(block: { 
            let img4 = Downloader.downloadImageWithURL(self.imageUrls[3]) 
             
            OperationQueue.main.addOperation({ 
                self.image4.image = img4 
                self.image4.clipsToBounds = true 
            }) 
        }) 
        op4.completionBlock = { print("image4 downloaded") } 
         
   //     op3.addDependency(op4) 
       // op2.addDependency(op3) 
         
        queue.addOperation (op1) 
        queue.addOperation(op4) 
        queue.addOperation(op3) 
        queue.addOperation(op2) 
    } 
} 
 
 
 
//GCD实用代码块 
 
import UIKit 
 
class ViewController: UIViewController { 
 
    @IBOutlet weak var image1: UIImageView! 
    @IBOutlet weak var image2: UIImageView! 
    @IBOutlet weak var image3: UIImageView! 
    @IBOutlet weak var image4: UIImageView! 
     
    let imageUrls = [ 
        "https://dn-boxueio.qbox.me/image1-big.jpg", 
        "https://dn-boxueio.qbox.me/image2-big.jpg", 
        "https://dn-boxueio.qbox.me/image3-big.jpg", 
        "https://dn-boxueio.qbox.me/image4-big.jpg" 
    ] 
     
    override func viewDidLoad() { 
        super.viewDidLoad() 
        // Do any additional setup after loading the view, typically from a nib. 
    } 
 
    override func didReceiveMemoryWarning() { 
        super.didReceiveMemoryWarning() 
        // Dispose of any resources that can be recreated. 
    } 
 
    @IBAction func clearDownload(_ sender: UIButton) { 
        self.image1.image = nil 
        self.image2.image = nil 
        self.image3.image = nil 
        self.image4.image = nil 
         
        URLCache.shared.removeAllCachedResponses() 
    } 
 
     func loadImageWithURL(_ url:String) -> UIImage! { 
        let data = try? Data(contentsOf: URL(string: url)!) 
        return UIImage(data: data!) 
         
         } 
 
     
    @IBAction func downloadImages(_ sender: UIButton) { 
         
       
        var currQueue = DispatchQueue.global(qos: .default) 
      //  currQueue = DispatchQueue(label: "com.boxueio.images", attributes: .concurrent) 
        //并行 
        currQueue=DispatchQueue(label: "currqueue1", qos: .default, attributes: .concurrent) 
         
        // dispatch_async 
        currQueue.async(execute: { 
            let img1 = self.loadImageWithURL(self.imageUrls[0]) 
            DispatchQueue.main.async(execute: { 
                self.image1.image = img1 
                self.image1.clipsToBounds = true 
            }) 
        }) 
         
        currQueue.async(execute: { 
            let img2 = self.loadImageWithURL(self.imageUrls[1]) 
            DispatchQueue.main.async(execute: { 
                self.image2.image = img2 
                self.image2.clipsToBounds = true 
            }) 
        }) 
         
        currQueue.async(execute: { 
            let img3 = Downloader.downloadImageWithURL(self.imageUrls[2]) 
            DispatchQueue.main.async(execute: { 
                self.image3.image = img3 
                self.image3.clipsToBounds = true 
            }) 
        }) 
         
        currQueue.async(execute: { 
            let img4 = Downloader.downloadImageWithURL(self.imageUrls[3]) 
            DispatchQueue.main.async(execute: { 
                self.image4.image = img4 
                self.image4.clipsToBounds = true 
            }) 
        }) 
    } 
} 
 
 
 
//class图片基类 
 
import UIKit 
class Downloader { 
     
    class func downloadImageWithURL(_ url:String) -> UIImage! { 
        let data = try? Data(contentsOf: URL(string: url)!) 
        return UIImage(data: data!) 
    } 
}