方法一:一般將服務器第一次返回的數據保存在沙盒裏面。這樣在手機斷網的情況下可以從本地讀取數據了。
1.保存到沙盒的代碼:
- + (void)saveCache:(int)type andID:(int)_id andString:(NSString *)str;
- {
- NSUserDefaults * setting = [NSUserDefaults standardUserDefaults];
- NSString * key = [NSString stringWithFormat:@"detail-%d-%d",type, _id];
- [setting setObject:str forKey:key];
- [setting synchronize];
- }
2.讀取本地沙盒的代碼
讀取之前首先根據type和Id判斷本地是否有
- + (NSString *)getCache:(int)type andID:(int)_id
- {
- NSUserDefaults * settings = [NSUserDefaults standardUserDefaults];
- NSString *key = [NSString stringWithFormat:@"detail-%d-%d",type, _id];
- NSString *value = [settings objectForKey:key];
- return value;
- }
如果沙盒裏面有數據
- NSString *value = [Tool getCache:5 andID:self.QiuTime];
- if (value) {
- NSDictionary *backdict = [value JSONValue];
- if ([backdict objectForKey:@"items"]) {
- NSArray *array=[NSArray arrayWithArray:[backdict objectForKey:@"items"]];
- for (NSDictionary *qiushi in array) {
- QiuShi *qs=[[[QiuShi alloc]initWithDictionary:qiushi] autorelease];
- [self.list addObject:qs];
- }
- }
- [self.tableView reloadData];
- }
- [self.tableView tableViewDidFinishedLoadingWithMessage:@"數據全部加載完了.."];
- self.tableView.reachedTheEnd = YES;
1、設置全局的Cache
在AppDelegate.h中添加一個全局變量
- @interface AppDelegate : UIResponder <UIApplicationDelegate>
- {
- ASIDownloadCache *myCache;
- }
- @property (strong, nonatomic) UIWindow *window;
- @property (nonatomic,retain) ASIDownloadCache *myCache;
在AppDelegate.m中的- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions方法中添加如下代碼
- //自定義緩存
- ASIDownloadCache *cache = [[ASIDownloadCache alloc] init];
- self.myCache = cache;
- [cache release];
- //設置緩存路徑
- NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
- NSString *documentDirectory = [paths objectAtIndex:0];
- [self.myCache setStoragePath:[documentDirectory stringByAppendingPathComponent:@"resource"]];
- [self.myCache setDefaultCachePolicy:ASIOnlyLoadIfNotCachedCachePolicy];
在AppDelegate.m中的dealloc方法中添加如下語句
- [myCache release];
到這裏爲止,就完成了全局變量的聲明。
2、設置緩存策略
在實現ASIHTTPRequest請求的地方設置request的存儲方式,代碼如下
- NSString *str = @"http://....../getPictureNews.aspx";
- NSURL *url = [NSURL URLWithString:str];
- ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
- //獲取全局變量
- AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
- //設置緩存方式
- [request setDownloadCache:appDelegate.myCache];
- //設置緩存數據存儲策略,這裏採取的是如果無更新或無法聯網就讀取緩存數據
- [request setCacheStoragePolicy:ASICachePermanentlyCacheStoragePolicy];
- request.delegate = self;
- [request startAsynchronous];
3、清理緩存數據
我在這裏採用的是手動清理數據的方式,在適當的地方添加如下代碼,我將清理緩存放在了應用的設置模塊:
- AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
- [appDelegate.myCache clearCachedResponsesForStoragePolicy:ASICachePermanentlyCacheStoragePolicy];
-----參考一:http://blog.csdn.net/kbawyg/article/details/7985513
-----參考二:http://zyc-to.blog.163.com/blog/static/17152400201110221340738/
備註:判斷手機是否有網絡 使用官方自帶的Reachability.h判斷
- -(BOOL)isNetworkRunning;
- {
- Reachability *r = [Reachability reachabilityWithHostName:@"http://www.baidu.com"];
- switch ([r currentReachabilityStatus]) {
- case NotReachable:
- return FALSE;
- break;
- case ReachableViaWWAN:
- return TRUE;
- break;
- case ReachableViaWiFi:
- return TRUE;
- break;
- }
- return FALSE;
- }
感謝原作 辛苦了