iOS 缓存 -- NSCache和沙盒缓存

1. 效果图

2.代码

import UIKit

class testView2: UIViewController {

    let cache = NSCache<AnyObject, AnyObject>()
    var imgeView = UIImageView()
    
    let imgUrl = "https://t7.baidu.com/it/u=4162611394,4275913936&fm=193&f=GIF"
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .white
        cache.countLimit = 10
        //cache.totalCostLimit = 1024
        cache.delegate = self
        setUI()
    }
    
    func setUI() {
        imgeView.frame = CGRect(x: 20, y: 100, width: UIScreen.main.bounds.size.width - 40, height: 350)
        view.addSubview(imgeView)
        
        let strArr = ["从网络读取数据","从内存缓存读取数据NSCache","删除ImageV","删除内存缓存NSCache","写入磁盘沙盒缓存","读取沙盒,并写入NSCache"]
        for i in 0..<6 {
            let btn = UIButton(frame: CGRect(x: 20, y: CGFloat(500 + i * 55), width: UIScreen.main.bounds.size.width - 40, height: 50))
            btn.layer.cornerRadius = 10
            btn.clipsToBounds = true
            btn.setTitle(strArr[i], for: .normal)
            btn.backgroundColor = UIColor(red: CGFloat(arc4random() % 255) / 255.0, green: CGFloat(arc4random() % 255) / 255.0, blue: CGFloat(arc4random() % 255) / 255.0, alpha: 1)
            btn.tag = i
            btn.addTarget(self, action: #selector(clickBtn(_:)), for: .touchUpInside)
            
            view.addSubview(btn)
        }
    }
}

@objc
extension testView2 {
    func clickBtn(_ sender: UIButton) {
        switch sender.tag {
        case 0:
            print("从网络读取数据")
            btn1()
        case 1:
            print("从内存缓存读取数据NSCache")
            btn2()
        case 2:
            print("删除ImageV")
            btn3()
        case 3:
            print("删除内存缓存NSCache")
            btn4()
        case 4:
            print("写入磁盘沙盒缓存")
            btn5()
        case 5:
            print("读取沙盒,并写入NSCache")
            btn6()
        default:
            break
        }
    }
    
    func btn1() {
        let session = URLSession.shared
        let url = NSURL(string: imgUrl)
        
        let downloadTask = session.dataTask(with: url! as URL) { [unowned self](data, res, error) in
            if error != nil {
                print("error:\(String(describing: error))")
                return
            }
            
            guard let imgData = data else {
                print("没获取到图片数据")
                return
            }
            
            self.cache.setObject(data as AnyObject, forKey: self.imgUrl as AnyObject)
            
            let diskPath = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).map(\.path).last
            let fileName = imgUrl.replacingOccurrences(of: "/", with: "")
            let fullpath = URL(fileURLWithPath: diskPath ?? "").appendingPathComponent(fileName).path
            let isSuccess = NSData(data: imgData).write(toFile: fullpath, atomically: true)
            if isSuccess {
                print("写入磁盘沙盒成功")
            }
            
            DispatchQueue.main.async {
                imgeView.image = UIImage(data: imgData)
            }
        }
        downloadTask.resume()
    }
    
    func btn2() {
        DispatchQueue.global(qos: .background).async {[unowned self] in
            let data = cache.object(forKey: imgUrl as AnyObject)
            if data != nil {
                DispatchQueue.main.async {
                    imgeView.image = UIImage(data: data as! Data)
                }
            } else {
                print("内存缓存中无数据")
            }
        }
    }
    
    func btn3() {
        imgeView.image = nil
    }
    
    func btn4() {
        cache.removeAllObjects()
    }
    
    func btn5() {
        // 下载的时候已经存
    }
    
    func btn6() {
        let diskPath = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).map(\.path).last
        let fileName = imgUrl.replacingOccurrences(of: "/", with: "")
        let fullPath = URL(fileURLWithPath: diskPath ?? "").appendingPathComponent(fileName).path
        print("diskPath:\(diskPath) \n fileName:\(fileName) \n fullPath:\(fullPath)")
        
        guard let imageData = NSData(contentsOfFile: fullPath) else {
            return
        }
        let imgData = imageData as Data
        
        imgeView.image = UIImage(data: imgData)
        cache.setObject(imgData as AnyObject, forKey: imgUrl as AnyObject)
        
        
    }
}

// NSCache
extension testView2: NSCacheDelegate {
    func cache(_ cache: NSCache<AnyObject, AnyObject>, willEvictObject obj: Any) {
        print("清除缓存",obj)
    }
}