iOS离线缓存

{      "resultcode": "200",      "reason": "Success",      "result": {   "data": [   {   "id": "1001",   "title": "糖醋小排",   "tags": "浙菜;热菜;儿童;酸甜;快手菜",   "imtro": "糖醋小排，我估计爱吃的人太多了，要想做好这道菜，关键就是调料汁的配置，老抽不能放的太多，那样颜色太重， 不好看，调料汁调好后，最好尝一下，每个人的口味都会不同的，可以适当微调一下哈！",   "ingredients": "肋排,500g",   "burden": "葱,适量;白芝麻,适量;盐,3g;生粉,45g;料酒,30ml;鸡蛋,1个;葱,1小段;姜,3片;老抽,7ml;醋,30ml;白糖,20g;番茄酱,15ml;生抽,15ml;生粉,7g;姜,适量",   "albums": [   "http://img.juhe.cn/cookbook/t/1/1001_253951.jpg"   ],   "steps": [   {   "img": "http://img.juhe.cn/cookbook/s/10/1001_40ec58177e146191.jpg",   "step": "1.排骨剁小块，用清水反复清洗，去掉血水"   },   {   "img": "http://img.juhe.cn/cookbook/s/10/1001_034906d012e61fcc.jpg",   "step": "2.排骨放入容器中，放入腌料，搅拌均匀，腌制5分钟"   },   {   "img": "http://img.juhe.cn/cookbook/s/10/1001_b04cddaea2a1a604.jpg",   "step": "3.锅中放适量油，烧至5成热，倒入排骨，炸至冒青烟时捞出，关火，等油温降至五成热时，开火，再次放入排骨，中火炸至焦黄、熟透捞出"   },   {   "img": "http://img.juhe.cn/cookbook/s/10/1001_56b92264df500f01.jpg",   "step": "4.锅中留少许底油，放入葱花、姜片爆香"   },   {   "img": "http://img.juhe.cn/cookbook/s/10/1001_d78c57536a08dc4b.jpg",   "step": "5.放入适量炸好的排骨，倒入调料汁，煮至汤汁浓稠时，关火，撒入葱花、白芝麻点缀即可"   }   ]   }   ],   "totalNum": 1,   "pn": 0,   "rn": 1   },      "error_code": 0  }

// 单例  +(SQLiteManager *)sharedInstance {      @synchronized(self) {          if (shareObj == nil) {              shareObj = [[self alloc] init];          }      }      return shareObj;  }

数据库初始化：

// 初始化数据库  -(instancetype)init {      if (self = [super init]) {          //文件路径          NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"step.sqlite"];          //初始化数据库          self.database = [FMDatabase databaseWithPath:path];          //打开数据库          [self.database open];          if ([self.database open]) {              //将step采用blob类型来存储              NSString *create = @"CREATE TABLE IF NOT EXISTS t_step(id integer PRIMARY KEY, step blob NOT NULL);";              [self.database executeUpdate:create];          }      }      return self;  }

//从数据库获取数据  -(NSArray *)stepsFromSqlite {      NSString *sql = @"SELECT * FROM t_step";      FMResultSet *set = [self.database executeQuery:sql];      NSMutableArray *steps = [NSMutableArray array];      while (set.next) {          NSData *data = [set objectForColumnName:@"step"];          Steps *step = [NSKeyedUnarchiver unarchiveObjectWithData:data];          [steps addObject:step];      }      return steps;  }

// 保存数据到数据库  -(void)saveSteps:(Steps *)step {      NSData *data = [NSKeyedArchiver archivedDataWithRootObject:step];      [self.database executeUpdateWithFormat:@"INSERT INTO t_step(step) VALUES (%@);", data];  }

//获取服务器数据  -(void)getData {      AFHTTPSessionManager *session = [[AFHTTPSessionManager alloc] init];      NSString *url = @"http://apis.juhe.cn/cook/queryid";      NSMutableDictionary *params = [NSMutableDictionary dictionary];      params[@"id"] = self.menuID;      params[@"key"] = self.appKey;      params[@"dtype"] = self.dtype;      //从数据库获取数据      NSArray *steps = [[SQLiteManager sharedInstance] stepsFromSqlite];      if (steps.count) {          self.stepsArray = [NSMutableArray arrayWithArray:steps];      } else {          //get请求，从服务器获取数据          [session GET:url parameters:params progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {              NSDictionary *result = responseObject[@"result"];              NSArray *data = result[@"data"];              for (NSDictionary *dict in data) {                  Menu *menu = [[Menu alloc] initWithDict:dict];                  self.stepsArray = menu.steps;              }              [self.tableView reloadData];          } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {              NSLog(@"error=%@",error);          }];      }  }

//字节大小  int byteSize = (int)[SDImageCache sharedImageCache].getSize;  //M大小  CGFloat cacheSize = byteSize / 1000.0 / 1000.0;  UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"清理缓存" message:[NSString stringWithFormat:@"缓存大小%.1fM",cacheSize] delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil];  [alert show];

//清除缓存  [[SDImageCache sharedImageCache] clearDisk];

注：文件夹是没有大小的，只有文件有大小属性。

//计算当前文件夹的大小  -(NSInteger)cachesFileSize {      //文件管理者      NSFileManager *mgr = [NSFileManager defaultManager];      //判断是否为文件      BOOL dir = NO;      BOOL exists = [mgr fileExistsAtPath:self isDirectory:&dir];      if (!exists) return 0;//说明文件或文件夹不存在      if (dir) { //self是一个文件夹          //遍历caches里面的内容 -- 直接和间接内容          NSArray *subpaths = [mgr subpathsAtPath:self];          NSInteger totalBytes = 0;          //如果self是一个文件夹，则遍历该文件夹下的文件          for (NSString *subpath in subpaths) {              //获得全路径              NSString *fullpath = [self stringByAppendingPathComponent:subpath];              BOOL directory = NO;              [mgr fileExistsAtPath:fullpath isDirectory:&directory];              if (!directory) { // self不是文件夹，计算文件的大小                  totalBytes += [[mgr attributesOfItemAtPath:fullpath error:nil][NSFileSize] integerValue];              }          }          return totalBytes;      } else { //self是一个文件          return [[mgr attributesOfItemAtPath:self error:nil][NSFileSize] integerValue];      }  }