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做网站用身份证,seo网站推广免费,网站建设需要的项目,wordpress推广提成1、ImageCache 使用内存缓存方式： 使用沙盒缓存方式： 使用网络图片第三方库方式： SDWebImage： iOS 中著名的网络图片处理框架包含的功能：图片下载、图片缓存、下载进度监听、gif 处理等等用法极其简单，功能…

1、ImageCache

使用内存缓存方式：
使用沙盒缓存方式：
使用网络图片第三方库方式：
- SDWebImage：
  - iOS 中著名的网络图片处理框架
  - 包含的功能：图片下载、图片缓存、下载进度监听、gif 处理等等
  - 用法极其简单，功能十分强大，大大提高了网络图片的处理效率
  - 国内超过 90% 的 iOS 项目都有它的影子
  - 1、图片文件缓存的时间有多长？
    - 1 周
```
    _maxCacheAge = kDefaultCacheMaxCacheAge;                                    // - (id)initWithNamespace: diskCacheDirectory:static const NSInteger kDefaultCacheMaxCacheAge = 60 * 60 * 24 * 7;         // 1 week   SDImageCache.m
```
  - 2、SDWebImage 的内存缓存是用什么实现的？
    - NSCache
  - 3、SDWebImage 的最大并发数是多少？
    - 是程序固定死了，可以通过属性进行调整！
```
    _downloadQueue.maxConcurrentOperationCount = 6;                             // SDWebImageDownloader.m   - (id)init
```
  - 4、网络访问超时时长
    - iOS 开发中，默认的访问时长是 1 分钟，SDWebImage 中是 15 秒。
```
    _downloadTimeout = 15.0;                                                    // SDWebImageDownloader.m   - (id)init
```
  - 5、SDWebImage 支持动图吗？GIF
    - 支持
```
    #import <ImageIO/ImageIO.h>                                                 // UIImage+GIF.m[UIImage animatedImageWithImages:images duration:duration];
```
  - 6、SDWebImage 是如何区分不同格式的图像的
    - 根据图像数据第一个字节来判断的！
```
    // NSData+ImageContentType.m    + (NSString *)sd_contentTypeForImageData:PNG：0x89 image/png ，压缩比没有 JPG 高，但是无损压缩，解压缩性能高，苹果推荐的图像格式！JPG：0xFF image/jpeg，压缩比最高的一种图片格式，有损压缩！最多使用的场景，照相机！解压缩的性能不好！GIF：0x47 image/gif ，序列桢动图，特点：只支持 256 种颜色！最流行的时候在 1998～1999，有专利的！
```
  - 7、SDWebImage 缓存图片的名称是怎么确定的！
    - md5
    - 如果单纯使用文件名保存，重名的几率很高！
    - 使用 MD5 的散列函数！对完整的 URL 进行 md5，结果是一个 32 个字符长度的字符串！
  - 8、SDWebImage 的内存警告是如何处理的！
    - 利用通知中心观察
    - UIApplicationDidReceiveMemoryWarningNotification 接收到内存警告的通知
    - 执行 clearMemory 方法，清理内存缓存！
    - UIApplicationWillTerminateNotification 接收到应用程序将要终止通知
    - 执行 cleanDisk 方法，清理磁盘缓存！
    - UIApplicationDidEnterBackgroundNotification 接收到应用程序进入后台通知
    - 执行 backgroundCleanDisk 方法，后台清理磁盘！
    - 通过以上通知监听，能够保证缓存文件的大小始终在控制范围之内！
    - clearDisk 清空磁盘缓存，将所有缓存目录中的文件，全部删除！实际工作，将缓存目录直接删除，再次创建一个同名空目录！
  - bug:
    - SDWebImage 中，一旦内存警告，清理了内存之后，之后所有的图片都是从沙盒加载的。
    - 原因：NSCache 中一旦调用了 removeAllObjects，就无法给 cache 添加对象。关于 NSCache 的内存管理，交给他自己就行！

2、自定义内存缓存方式

Objective-C

AppInfoModel.h

    @interface AppInfoModel : NSObject/// 标题名称@property (nonatomic, strong) NSString *name;/// 下载数量@property (nonatomic, strong) NSString *download;/// 图片地址@property (nonatomic, strong) NSString *icon;/// 声明工厂方法，数据源初始化方法+ (instancetype)appInfoModelWithDict:(NSDictionary *)dict;@end

AppInfoModel.m

    // 实现工厂方法+ (instancetype)appInfoModelWithDict:(NSDictionary *)dict {id obj = [[self alloc] init];[obj setValuesForKeysWithDictionary:dict];return obj;}

AppInfoCell.h

    @interface AppInfoCell : UITableViewCell@property (nonatomic, weak) IBOutlet UILabel *nameLabel;@property (nonatomic, weak) IBOutlet UILabel *downloadLabel;@property (nonatomic, weak) IBOutlet UIImageView *iconImageView;@end

ViewController.m

    /// 表格数据源@property (nonatomic, strong) NSArray *dataSourceArray;/// 图片下载队列@property (nonatomic, strong) NSOperationQueue *downloadQueue;/// 下载缓冲池@property (nonatomic, strong) NSMutableDictionary *downloadQueueCache;/// 图片缓冲池@property (nonatomic, strong) NSMutableDictionary *imageCache;/// 图片下载地址黑名单@property (nonatomic, retain) NSMutableArray *urlBlackList;// 懒加载- (NSArray *)dataSourceArray {if (_dataSourceArray == nil) {NSArray *array = [NSArray arrayWithContentsOfURL:[[NSBundle mainBundle] URLForResource:@"apps.plist" withExtension:nil]];NSMutableArray *arrayM = [NSMutableArray arrayWithCapacity:array.count];[array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {[arrayM addObject:[AppInfoModel appInfoModelWithDict:obj]];}];_dataSourceArray = [arrayM copy];}return _dataSourceArray;}- (NSOperationQueue *)downloadQueue {if (_downloadQueue == nil) {_downloadQueue = [[NSOperationQueue alloc] init];}return _downloadQueue;}- (NSMutableDictionary *)downloadQueueCache {if (_downloadQueueCache == nil) {_downloadQueueCache = [[NSMutableDictionary alloc] init];}return _downloadQueueCache;}- (NSMutableDictionary *)imageCache {if (_imageCache == nil) {_imageCache = [[NSMutableDictionary alloc] init];}return _imageCache;}- (NSMutableArray *)urlBlackList {if (_urlBlackList == nil) {_urlBlackList = [[NSMutableArray alloc] init];}return _urlBlackList;}// 表格视图数据源方法- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {return self.dataSourceArray.count;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {AppInfoCell *cell = [tableView dequeueReusableCellWithIdentifier:@"AppCell" forIndexPath:indexPath];AppInfoModel *dataModel = self.dataSourceArray[indexPath.row];cell.nameLabel.text = dataModel.name;cell.downloadLabel.text = dataModel.download;// 判断图片缓存池中是否有相应的图片if (self.imageCache[dataModel.icon] != nil) {                                                           // 从缓存池中取出图片显示在 Cell 上cell.iconImageView.image = self.imageCache[dataModel.icon];} else {// 从网络异步下载图片[self downloadImageWithIndexPath:indexPath];}return cell;}- (void)downloadImageWithIndexPath:(NSIndexPath *)indexPath {AppInfoModel *dataModel = self.dataSourceArray[indexPath.row];// 判断下载缓冲池中是否存在当前下载操作if (self.downloadQueueCache[dataModel.icon] != nil) {return;}// 判断图片地址是否在黑名单中if ([self.urlBlackList containsObject:dataModel.icon]) {return;}// 创建异步下载图片操作NSBlockOperation *downloadOperation = [NSBlockOperation blockOperationWithBlock:^{UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:dataModel.icon]]];// 下载完成从下载缓冲池中删除当前下载操作[self.downloadQueueCache removeObjectForKey:dataModel.icon];// 添加黑名单记录if (image == nil && ![self.urlBlackList containsObject:dataModel.icon]) {[self.urlBlackList addObject:dataModel.icon];}// 主线程跟新 UI[[NSOperationQueue mainQueue] addOperationWithBlock:^{if (image != nil) {// 将下载完成的图片保存到图片缓冲池中[self.imageCache setObject:image forKey:dataModel.icon];[self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];}}];}];// 将当前下载添加到下载缓冲池中[self.downloadQueueCache setObject:downloadOperation forKey:dataModel.icon];// 开始异步下载图片[self.downloadQueue addOperation:downloadOperation];}// 内存警告/*日常上课通常就直接删除，但是在工作后，必须要处理！不处理后果很严重，第一次内存警告如果不处理，就没有第二次的机会了，就直接被闪退了*/- (void)didReceiveMemoryWarning {[super didReceiveMemoryWarning];// 清理缓冲池[self.downloadQueueCache removeAllObjects];[self.imageCache removeAllObjects];// 取消下载操作，等用户再滚动表格，调用数据源方法，又能够自动下载[self.downloadQueue cancelAllOperations];}

Swift

AppInfo.swift

    class AppInfo: NSObject {var name:String!var icon:String!var download:String!class func AppInfoWithDict(dict:[String:AnyObject]) -> AnyObject {let obj:AnyObject = self.init()obj.setValuesForKeysWithDictionary(dict)return obj}required override init() {super.init()}}

AppInfoCell.swift

    class AppInfoCell: UITableViewCell {@IBOutlet weak var iconView: UIImageView!@IBOutlet weak var nameLabel: UILabel!@IBOutlet weak var downLabel: UILabel!}

ViewController.swift

    // 懒加载// 数据源lazy var dataSourceArray:[AnyObject] = {var dataArray:[AnyObject] = Array()let array = NSArray(contentsOfURL: NSBundle.mainBundle().URLForResource("apps.plist", withExtension: nil)!)array!.enumerateObjectsUsingBlock { (obj:AnyObject, idx:Int, stop:UnsafeMutablePointer<ObjCBool>) indataArray.append(AppInfoModel.AppInfoWithDict(obj as! [String : AnyObject]))}return dataArray}()// 下载队列lazy var downloadQueue:NSOperationQueue = {var tmp:NSOperationQueue = NSOperationQueue()return tmp}()// 下载缓冲池lazy var downloadQueueCache:[String:NSBlockOperation] = {var tmp:[String:NSBlockOperation] = Dictionary()return tmp}()// 图片缓冲池lazy var imageCache:[String:UIImage] = {var tmp:[String:UIImage] = Dictionary()return tmp}()// 图片下载地址黑名单lazy var urlBlackList:[String] = {var tmp:[String] = Array()return tmp}()// 表格视图数据源方法override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {return self.dataSourceArray.count}override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {let cell:AppInfoCell = tableView.dequeueReusableCellWithIdentifier("AppCell", forIndexPath: indexPath) as! AppInfoCelllet dataModel = self.dataSourceArray[indexPath.row] as! AppInfoModelcell.nameLabel.text = dataModel.namecell.downLabel.text = dataModel.download// 判断图片缓存池中是否有相应的图片if self.imageCache[dataModel.icon] != nil {// 从缓存池中取出图片显示在 Cell 上cell.iconView.image = self.imageCache[dataModel.icon]} else {// 从网络异步下载图片self.downloadImageWithIndexPath(indexPath)}return cell}func downloadImageWithIndexPath(indexPath:NSIndexPath) {let dataModel = self.dataSourceArray[indexPath.row] as! AppInfoModel// 判断下载缓冲池中是否存在当前下载操作if self.downloadQueueCache[dataModel.icon] != nil {return}// 判断图片地址是否在黑名单中if self.urlBlackList.contains(dataModel.icon) {return}// 创建异步下载图片操作let downloadOperation = NSBlockOperation {let image:UIImage? = UIImage(data: NSData(contentsOfURL: NSURL(string: dataModel.icon)!)!)// 下载完成从下载缓冲池中删除当前下载操作self.downloadQueueCache.removeValueForKey(dataModel.icon)// 添加黑名单记录if image == nil && !self.urlBlackList.contains(dataModel.icon) {self.urlBlackList.append(dataModel.icon)}// 主线程跟新 UINSOperationQueue.mainQueue().addOperationWithBlock({if image != nil {// 将下载完成的图片保存到图片缓冲池中self.imageCache[dataModel.icon] = imageself.tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .Automatic)}})}// 将当前下载添加到下载缓冲池中self.downloadQueueCache[dataModel.icon] = downloadOperation// 开始异步下载图片self.downloadQueue.addOperation(downloadOperation)}// 内存警告override func didReceiveMemoryWarning() {super.didReceiveMemoryWarning()self.downloadQueueCache.removeAll()self.imageCache.removeAll()self.downloadQueue.cancelAllOperations()}

3、自定义沙盒缓存方式

Objective-C

AppInfoModel.h
AppInfoModel.m
AppInfoCell.h
- 与上边一样

NSString+BundlePath.h

    ///  拼接缓存目录- (NSString *)appendCachePath;

NSString+BundlePath.m

    - (NSString *)appendCachePath {NSString *dir = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).lastObject;return [dir stringByAppendingPathComponent:self.lastPathComponent];}

ViewController.m

    // 懒加载与上边一样// 表格视图数据源方法- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {return self.dataSourceArray.count;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {AppInfoCell *cell = [tableView dequeueReusableCellWithIdentifier:@"AppCell" forIndexPath:indexPath];AppInfoModel *dataModel = self.dataSourceArray[indexPath.row];cell.nameLabel.text = dataModel.name;cell.downloadLabel.text = dataModel.download;// 判断图片缓存池中是否有相应的图片if (self.imageCache[dataModel.icon] != nil) {// 从缓存池中取出图片显示在 Cell 上cell.iconImageView.image = self.imageCache[dataModel.icon];                                         } else {// 从沙盒加载图片UIImage *image = [UIImage imageWithContentsOfFile:[dataModel.icon appendCachePath]];if (image != nil) {cell.iconImageView.image = image;self.imageCache[dataModel.icon] = image;} else {// 从网络异步下载图片[self downloadImageWithIndexPath:indexPath];}}return cell;}- (void)downloadImageWithIndexPath:(NSIndexPath *)indexPath {AppInfoModel *dataModel = self.dataSourceArray[indexPath.row];// 判断下载缓冲池中是否存在当前下载操作if (self.downloadQueueCache[dataModel.icon] != nil) {return;}// 判断图片地址是否在黑名单中if ([self.urlBlackList containsObject:dataModel.icon]) {                                                return;}// 创建异步下载图片操作NSBlockOperation *downloadOperation = [NSBlockOperation blockOperationWithBlock:^{NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:dataModel.icon]];UIImage *image = [UIImage imageWithData:imageData];// 下载完成从下载缓冲池中删除当前下载操作[self.downloadQueueCache removeObjectForKey:dataModel.icon];// 添加黑名单记录if (image == nil && ![self.urlBlackList containsObject:dataModel.icon]) {[self.urlBlackList addObject:dataModel.icon];}if (image != nil) {// 将图像写入沙盒[imageData writeToFile:[dataModel.icon appendCachePath] atomically:YES];}// 主线程跟新 UI[[NSOperationQueue mainQueue] addOperationWithBlock:^{if (image != nil) {// 将下载完成的图片保存到图片缓冲池中[self.imageCache setObject:image forKey:dataModel.icon];[self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];}}];}];// 将当前下载添加到下载缓冲池中[self.downloadQueueCache setObject:downloadOperation forKey:dataModel.icon];// 开始异步下载图片[self.downloadQueue addOperation:downloadOperation];}// 内存警告与上边一样

Swift

AppInfo.swift
AppInfoCell.swift
- 与上边一样

String+BundlePath.swift

    public func appendCachePath() -> String? {let dir:String? = NSSearchPathForDirectoriesInDomains(.CachesDirectory, .UserDomainMask, true).lastif (dir != nil) {return dir! + "/" + (self as NSString).lastPathComponent} else {return nil}}

ViewController.swift

    // 懒加载与上边一样// 表格视图数据源方法override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {return self.dataSourceArray.count}override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {let cell:AppInfoCell = tableView.dequeueReusableCellWithIdentifier("AppCell", forIndexPath: indexPath) as! AppInfoCelllet dataModel = self.dataSourceArray[indexPath.row] as! AppInfoModelcell.nameLabel.text = dataModel.namecell.downLabel.text = dataModel.download// 判断图片缓存池中是否有相应的图片if self.imageCache[dataModel.icon] != nil {// 从缓存池中取出图片显示在 Cell 上cell.iconView.image = self.imageCache[dataModel.icon]} else {// 从沙盒加载图片let image = UIImage(contentsOfFile: dataModel.icon.appendCachePath()!)if (image != nil) {cell.iconView.image = imageself.imageCache[dataModel.icon] = image} else {// 从网络异步下载图片self.downloadImageWithIndexPath(indexPath)}}return cell}func downloadImageWithIndexPath(indexPath:NSIndexPath) {let dataModel = self.dataSourceArray[indexPath.row] as! AppInfoModel// 判断下载缓冲池中是否存在当前下载操作if self.downloadQueueCache[dataModel.icon] != nil {return}// 判断图片地址是否在黑名单中if self.urlBlackList.contains(dataModel.icon) {return}// 创建异步下载图片操作let downloadOperation = NSBlockOperation {let imageData:NSData? = NSData(contentsOfURL: NSURL(string: dataModel.icon)!)let image:UIImage? = UIImage(data: imageData!)// 下载完成从下载缓冲池中删除当前下载操作self.downloadQueueCache.removeValueForKey(dataModel.icon)// 添加黑名单记录if image == nil && !self.urlBlackList.contains(dataModel.icon) {self.urlBlackList.append(dataModel.icon)}if image != nil {// 将图像写入沙盒imageData!.writeToFile(dataModel.icon.appendCachePath()!, atomically: true)print(dataModel.icon.appendCachePath()!)}// 主线程跟新 UINSOperationQueue.mainQueue().addOperationWithBlock({if image != nil {// 将下载完成的图片保存到图片缓冲池中self.imageCache[dataModel.icon] = image                                                             self.tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .Automatic)}})}// 将当前下载添加到下载缓冲池中self.downloadQueueCache[dataModel.icon] = downloadOperation// 开始异步下载图片self.downloadQueue.addOperation(downloadOperation)}// 内存警告与上边一样

4、仿 SDWebImage 缓存方式

Objective-C

AppInfoModel.h

    @interface AppInfoModel : NSObject/// 标题名称@property (nonatomic, strong) NSString *name;/// 下载数量@property (nonatomic, strong) NSString *download;/// 图片地址@property (nonatomic, strong) NSString *icon;/// 从 Plist 加载 AppInfo+ (NSArray *)loadPList;@end

AppInfoModel.m

    + (NSArray *)loadPList {NSArray *array = [NSArray arrayWithContentsOfURL:[[NSBundle mainBundle] URLForResource:@"apps.plist" withExtension:nil]];NSMutableArray *plist = [NSMutableArray arrayWithCapacity:array.count];[array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {id model = [[self alloc] init];[model setValuesForKeysWithDictionary:obj];[plist addObject:model];}];return plist;}

AppInfoCell.h

    @interface AppInfoCell : UITableViewCell@property (nonatomic, weak) IBOutlet UILabel *nameLabel;@property (nonatomic, weak) IBOutlet UILabel *downloadLabel;@property (nonatomic, weak) IBOutlet UIImageView *iconImageView;@end

NSString+BundlePath.h

    ///  拼接缓存目录- (NSString *)appendCachePath;

NSString+BundlePath.m

    - (NSString *)appendCachePath {NSString *dir = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).lastObject;return [dir stringByAppendingPathComponent:self.lastPathComponent];}

WebImageOperation.h

    @interface WebImageOperation : NSOperation///  实例化 web 图像操作+ (instancetype)webImageOperationWithURLString:(NSString *)urlString completion:(void (^)(UIImage *image))completion;@end

WebImageOperation.m

    /// 下载图片的 URL@property (nonatomic, copy) NSString *urlStr;/// 下载完成的回调@property (nonatomic, copy) void (^completion) (UIImage *image);+ (instancetype)webImageOperationWithURLString:(NSString *)urlString completion:(void (^)(UIImage *))completion {WebImageOperation *imageOperation = [[self alloc] init];imageOperation.urlStr= urlString;imageOperation.completion = completion;return imageOperation;}// 操作加入队列后会自动执行该方法- (void)main {@autoreleasepool {if (self.isCancelled) return;NSURL *url = [NSURL URLWithString:self.urlStr];NSData *data = [NSData dataWithContentsOfURL:url];if (self.isCancelled) return;if (data != nil) {[data writeToFile:self.urlStr.appendCachePath atomically:YES];}if (self.isCancelled) return;if (self.completion && data != nil) {[[NSOperationQueue mainQueue] addOperationWithBlock:^{self.completion([UIImage imageWithData:data]);  }];}}}

WebImageManager.h

    //  负责所有网络图像的下载操作以及缓存管理！@interface WebImageManager : NSObject///  全局单例访问入口+ (instancetype)sharedManager;///  下载网络图像- (void)downloadImage:(NSString *)urlString completion:(void (^) (UIImage *image))completion;///  取消 urlString 对应的下载操作- (void)cancelDownload:(NSString *)urlString;@end

WebImageManager.m

    /// 下载队列@property (nonatomic, strong) NSOperationQueue *downloadQueue;/// 下载操作缓冲池@property (nonatomic, strong) NSMutableDictionary *downloadQueueCache;/// 图片缓冲池@property (nonatomic, strong) NSMutableDictionary *imageCache;// 下载管理器// 实例化下载管理器+ (instancetype)sharedManager {static id instance;static dispatch_once_t onceToken;dispatch_once(&onceToken, ^{instance = [[self alloc] init];});return instance;}// 下载操作- (void)downloadImage:(NSString *)urlString completion:(void (^)(UIImage *))completion {// 判断缓存中是否存在图像if ([self checkCacheWithURLString:urlString]) {if (completion != nil) {// 直接回调，传递给调用方图像completion(self.imageCache[urlString]);}return;}// 判断缓冲池中是否存在下载操作if (self.downloadQueueCache[urlString] != nil) {return;}WebImageOperation *downloadOperation = [WebImageOperation webImageOperationWithURLString:urlString completion:^(UIImage *image) {// 下载完成从操作缓冲池中移除操作[self.downloadQueueCache removeObjectForKey:urlString];// 下载完成添加到图片缓冲池中[self.imageCache setObject:image forKey:urlString];if (completion != nil) {completion(image);}}];// 将操作添加到缓冲池[self.downloadQueueCache setObject:downloadOperation forKey:urlString];// 将操作添加到队列[self.downloadQueue addOperation:downloadOperation];}// 取消 urlString 对应的下载操作- (void)cancelDownload:(NSString *)urlString {// 从缓冲池拿到下载操作WebImageOperation *downloadOperation = self.downloadQueueCache[urlString];if (downloadOperation != nil) {// 取消操作[downloadOperation cancel];// 从缓冲池中删除操作[self.downloadQueueCache removeObjectForKey:urlString];}}// 判断缓存中是否存在图像- (BOOL)checkCacheWithURLString:(NSString *)urlString {// 判断图片缓冲池中是否存在图像if (self.imageCache[urlString] != nil) {return YES;}UIImage *image = [UIImage imageWithContentsOfFile:[urlString appendCachePath]];// 判断沙盒中是否存在图像if (image != nil) {[self.imageCache setObject:image forKey:urlString];return YES;}return NO;}// 懒加载- (NSOperationQueue *)downloadQueue {if (_downloadQueue == nil) {_downloadQueue = [[NSOperationQueue alloc] init];}return _downloadQueue;}- (NSMutableDictionary *)downloadQueueCache {if (_downloadQueueCache == nil) {_downloadQueueCache = [[NSMutableDictionary alloc] init];}return _downloadQueueCache;}- (NSMutableDictionary *)imageCache {if (_imageCache == nil) {_imageCache = [[NSMutableDictionary alloc] init];}return _imageCache;}

UIImageView+WebImageView.h

    @interface UIImageView (WebImageView)/// 设置 Web 图像 URL，自动加载图像- (void)setWebImageWithURL:(NSString *)urlString;@end

UIImageView+WebImageView.m

    #import <objc/runtime.h>// 下载图片的 url@property (nonatomic, copy) NSString *urlStr;- (void)setWebImageWithURL:(NSString *)urlString {// 屏蔽快速滑动重复添加下载if ([self.urlStr isEqualToString:urlString]) {return;}// 暂停之前的操作if (self.urlStr != nil && ![self.urlStr isEqualToString:urlString]) {[[WebImageManager sharedManager] cancelDownload:self.urlStr];// 如果 ImageView 之前有图像-清空图像self.image = nil;}// 记录新的 urlself.urlStr = urlString;__weak typeof(self) weakSelf = self;// 下载网络图片[[WebImageManager sharedManager] downloadImage:self.urlStr completion:^(UIImage *image) {weakSelf.image = image;}];}// 向分类添加属性// 运行时的关联对象，动态添加属性const void *URLStrKey = "URLStrKey";- (void)setUrlStr:(NSString *)urlString {objc_setAssociatedObject(self, URLStrKey, urlString, OBJC_ASSOCIATION_COPY_NONATOMIC);}- (NSString *)urlStr {return objc_getAssociatedObject(self, URLStrKey);}

ViewController.m

    /// 表格数据源@property (nonatomic, strong) NSArray *dataSourceArray;// 懒加载- (NSArray *)dataSourceArray {if (_dataSourceArray == nil) {_dataSourceArray = [AppInfoModel loadPList];}return _dataSourceArray;}// 表格视图数据源方法- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {return self.dataSourceArray.count;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {AppInfoCell *cell = [tableView dequeueReusableCellWithIdentifier:@"AppCell" forIndexPath:indexPath];AppInfoModel *dataModel = self.dataSourceArray[indexPath.row];cell.nameLabel.text = dataModel.name;cell.downloadLabel.text = dataModel.download;[cell.iconImageView setWebImageWithURL:dataModel.icon];return cell;}

Swift

AppInfoModel.swift

    class AppInfoModel: NSObjectvar name:String!var icon:String!var download:String!class func loadPList() -> [AnyObject] {let array = NSArray(contentsOfURL: NSBundle.mainBundle().URLForResource("apps.plist", withExtension: nil)!)var plist:[AnyObject] = Array()array!.enumerateObjectsUsingBlock { (obj:AnyObject, idx:Int, stop:UnsafeMutablePointer<ObjCBool>) inlet model:AnyObject = self.init()model.setValuesForKeysWithDictionary(obj as! [String : AnyObject])plist.append(model)}return plist}class func AppInfoWithDict(dict:[String:AnyObject]) -> AnyObject {let obj:AnyObject = self.init()obj.setValuesForKeysWithDictionary(dict)return obj}required override init() {super.init()}

AppInfoCell.swift

    @IBOutlet weak var iconView: UIImageView!@IBOutlet weak var nameLabel: UILabel!@IBOutlet weak var downLabel: UILabel!

String+BundlePath.swift

    ///  拼接缓存目录public func appendCachePath() -> String? {let dir:String? = NSSearchPathForDirectoriesInDomains(.CachesDirectory, .UserDomainMask, true).lastif (dir != nil) {return dir! + "/" + (self as NSString).lastPathComponent} else {return nil}}

WebImageOperation.swift

    class WebImageOperation: NSOperation/// 下载图片的 URLvar urlStr:String!/// 下载完成的回调var completion:((image:UIImage) -> Void)!class func webImageOperationWithURLString(urlString:String, completion:((image:UIImage) -> Void)) -> WebImageOperation {let imageOperation:WebImageOperation = WebImageOperation()imageOperation.urlStr = urlStringimageOperation.completion = completionreturn imageOperation}// 操作加入队列后会自动执行该方法override func main() {if self.cancelled == true {return}let url:NSURL = NSURL(string: self.urlStr)!let data:NSData? = NSData(contentsOfURL: url)if self.cancelled == true {return}if data != nil {data?.writeToFile(self.urlStr.appendCachePath()!, atomically: true)}if self.cancelled == true {return}if (self.completion != nil) && (data != nil) {NSOperationQueue.mainQueue().addOperationWithBlock({self.completion(image: UIImage(data: data!)!)})}}

WebImageManager.swift

    // 负责所有网络图像的下载操作以及缓存管理！class WebImageManager: NSObject// 下载队列lazy var downloadQueue:NSOperationQueue = {var tmp:NSOperationQueue = NSOperationQueue()return tmp}()// 下载缓冲池lazy var downloadQueueCache:[String:WebImageOperation] = {var tmp:[String:WebImageOperation] = Dictionary()return tmp}()// 图片缓冲池lazy var imageCache:[String:UIImage] = {var tmp:[String:UIImage] = Dictionary()return tmp}()// 下载管理器static let sharedManager = WebImageManager()private override init() {}// 下载操作func downloadImage(urlString:String, completion:((image:UIImage) -> Void)?) {// 判断缓存中是否存在图像if self.checkCacheWithURLString(urlString) == true {if completion != nil {// 直接回调，传递给调用方图像completion!(image: self.imageCache[urlString]!)}return}// 判断缓冲池中是否存在下载操作if self.downloadQueueCache[urlString] != nil {print("玩命下载中...稍安勿躁!")return}let downloadOperation:WebImageOperation = WebImageOperation.webImageOperationWithURLString(urlString) { (image) in// 下载完成从操作缓冲池中移除操作self.downloadQueueCache.removeValueForKey(urlString)// 下载完成添加到图片缓冲池中self.imageCache[urlString] = imageif (completion != nil) {completion!(image: image);}}// 将操作添加到缓冲池self.downloadQueueCache[urlString] = downloadOperation// 将操作添加到队列self.downloadQueue.addOperation(downloadOperation)}// 取消 urlString 对应的下载操作func cancelDownload(urlString:String) {// 从缓冲池拿到下载操作let downloadOperation:WebImageOperation? = self.downloadQueueCache[urlString]if downloadOperation != nil {print("取消下载操作")// 取消操作downloadOperation!.cancel()// 从缓冲池中删除操作self.downloadQueueCache.removeValueForKey(urlString)}}// 判断缓存中是否存在图像func checkCacheWithURLString(urlString:String) -> Bool {// 判断图片缓冲池中是否存在图像if self.imageCache[urlString] != nil {print("从内存中加载...")return true}let image:UIImage? = UIImage(contentsOfFile: urlString.appendCachePath()!)// 判断沙盒中是否存在图像if image != nil {print("从沙盒中加载...")self.imageCache[urlString] = imagereturn true}return false}

UIImageView+WebImageView.h

    @interface UIImageView (WebImageView)/// 设置 Web 图像 URL，自动加载图像- (void)setWebImageWithURL:(NSString *)urlString;@end

UIImageView+WebImageView.m

    #import <objc/runtime.h>#import "SwiftImageCache-Swift.h"// 下载图片的 url@property (nonatomic, copy) NSString *urlStr;- (void)setWebImageWithURL:(NSString *)urlString {// 屏蔽快速滑动重复添加下载if ([self.urlStr isEqualToString:urlString]) {return;}// 暂停之前的操作if (self.urlStr != nil && ![self.urlStr isEqualToString:urlString]) {[[WebImageManager sharedManager] cancelDownload:self.urlStr];// 如果 ImageView 之前有图像-清空图像self.image = nil;}// 记录新的 urlself.urlStr = urlString;__weak typeof(self) weakSelf = self;// 下载网络图片[[WebImageManager sharedManager] downloadImage:self.urlStr completion:^(UIImage *image) {weakSelf.image = image;}];}// 向分类添加属性// 运行时的关联对象，动态添加属性const void *URLStrKey = "URLStrKey";- (void)setUrlStr:(NSString *)urlString {objc_setAssociatedObject(self, URLStrKey, urlString, OBJC_ASSOCIATION_COPY_NONATOMIC);}- (NSString *)urlStr {return objc_getAssociatedObject(self, URLStrKey);}

SwiftImageCache-Bridging-Header.h

    #import "UIImageView+WebImageView.h"

ViewController.swift

    // 懒加载lazy var dataSourceArray:[AnyObject] = {var tmp:[AnyObject] = AppInfoModel.loadPList()return tmp}()// 表格视图数据源方法override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {return self.dataSourceArray.count}override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {let cell:AppInfoCell = tableView.dequeueReusableCellWithIdentifier("AppCell", forIndexPath: indexPath) as! AppInfoCelllet dataModel = self.dataSourceArray[indexPath.row] as! AppInfoModelcell.nameLabel.text = dataModel.namecell.downLabel.text = dataModel.downloadcell.iconView.setWebImageWithURL(dataModel.icon)return cell}

5、SDWebImage 缓存方式

Github 网址：https://github.com/rs/SDWebImage
SDWebImage 使用 ARC

Objective-C

    // 添加第三方库文件SDWebImage// 包含头文件#import "UIImageView+WebCache.h"

AppInfoModel.h

    @interface AppInfoModel : NSObject/// 标题名称@property (nonatomic, strong) NSString *name;/// 下载数量@property (nonatomic, strong) NSString *download;/// 图片地址@property (nonatomic, strong) NSString *icon;/// 从 Plist 加载 AppInfo+ (NSArray *)loadPList;@end

AppInfoModel.m

    + (NSArray *)loadPList {NSArray *array = [NSArray arrayWithContentsOfURL:[[NSBundle mainBundle] URLForResource:@"apps.plist" withExtension:nil]];NSMutableArray *plist = [NSMutableArray arrayWithCapacity:array.count];[array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {id model = [[self alloc] init];[model setValuesForKeysWithDictionary:obj];[plist addObject:model];}];return plist;}

AppInfoCell.h

    @interface AppInfoCell : UITableViewCell@property (nonatomic, weak) IBOutlet UILabel *nameLabel;@property (nonatomic, weak) IBOutlet UILabel *downloadLabel;@property (nonatomic, weak) IBOutlet UIImageView *iconImageView;@end

ViewController.m

    /// 表格数据源@property (nonatomic, strong) NSArray *dataSourceArray;// 懒加载- (NSArray *)dataSourceArray {if (_dataSourceArray == nil) {_dataSourceArray = [AppInfoModel loadPList];}return _dataSourceArray;}// 表格视图数据源方法- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {return self.dataSourceArray.count;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {AppInfoCell *cell = [tableView dequeueReusableCellWithIdentifier:@"AppCell" forIndexPath:indexPath];AppInfoModel *dataModel = self.dataSourceArray[indexPath.row];cell.nameLabel.text = dataModel.name;cell.downloadLabel.text = dataModel.download;[cell.iconImageView sd_setImageWithURL:[NSURL URLWithString:dataModel.icon]];return cell;}

Swift

    // 添加第三方库文件SDWebImage// 创建桥接头文件，如SwiftImageCache-Bridging-Header.h// 在桥接头文件中添加头文件#import "UIImageView+WebCache.h"

AppInfoModel.swift

    class AppInfoModel: NSObject    var name:String!var icon:String!var download:String!class func loadPList() -> [AnyObject] {let array = NSArray(contentsOfURL: NSBundle.mainBundle().URLForResource("apps.plist", withExtension: nil)!)var plist:[AnyObject] = Array()array!.enumerateObjectsUsingBlock { (obj:AnyObject, idx:Int, stop:UnsafeMutablePointer<ObjCBool>) inlet model:AnyObject = self.init()model.setValuesForKeysWithDictionary(obj as! [String : AnyObject])plist.append(model)}return plist}class func AppInfoWithDict(dict:[String:AnyObject]) -> AnyObject {let obj:AnyObject = self.init()obj.setValuesForKeysWithDictionary(dict)return obj}required override init() {super.init()}

AppInfoCell.swift

    class AppInfoCell: UITableViewCell  @IBOutlet weak var iconView: UIImageView!@IBOutlet weak var nameLabel: UILabel!@IBOutlet weak var downLabel: UILabel!

ViewController.swift

    // 懒加载lazy var dataSourceArray:[AnyObject] = {var tmp:[AnyObject] = AppInfoModel.loadPList()return tmp}()// 表格视图数据源方法override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {return self.dataSourceArray.count}override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {let cell:AppInfoCell = tableView.dequeueReusableCellWithIdentifier("AppCell", forIndexPath: indexPath) as! AppInfoCelllet dataModel = self.dataSourceArray[indexPath.row] as! AppInfoModelcell.nameLabel.text = dataModel.namecell.downLabel.text = dataModel.download// 设置图片cell.iconView.sd_setImageWithURL(NSURL(string: dataModel.icon))return cell}

转载于:https://www.cnblogs.com/QianChia/p/5769305.html

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