一，代码。
AppDelegate.h
#import <UIKit/UIKit.h>@interface AppDelegate : UIResponder <UIApplicationDelegate>{ NSMutableDictionary *cachedData;}@property (strong, nonatomic) UIWindow *window;@end
AppDelegate.m
#import "AppDelegate.h"#import "RootViewController.h"@implementation AppDelegate- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{ self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; // Override point for customization after application launch. RootViewController *rootVC=[[RootViewController alloc]init]; UINavigationController *nav=[[UINavigationController alloc]initWithRootViewController:rootVC]; self.window.rootViewController=nav; self.window.backgroundColor = [UIColor whiteColor]; [self.window makeKeyAndVisible]; return YES;}#pragma mark - 缓存- (void)initCachedCapacity;{ if (!cachedData) { cachedData = [[NSMutableDictionary alloc] init]; } [cachedData removeAllObjects]; [self readDataFromFile:@"cachedData" toTheData:cachedData]; NSLog(@"initCachedCapacity");}- (void)saveCachedCapacity{ NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults]; [self saveDataToFile:cachedData theFileName:@"cachedData"]; [userDefaults synchronize]; NSLog(@"saveCachedCapacity");}#pragma mark - 缓存路径操作类// 返回文件路径- (NSString *)dataFilePath:(NSString *)fileName { NSString *homeDirectory= [NSHomeDirectory() stringByAppendingPathComponent:@"tmp"]; NSString *filePhyPath=[homeDirectory stringByAppendingPathComponent:fileName]; return filePhyPath;}// 存储数据到文件- (void)saveDataToFile:(id)paramData theFileName:(NSString *)paramName{ NSString *savePath=[self dataFilePath:paramName]; if ([paramData isKindOfClass:[NSMutableDictionary class]]) { [paramData writeToFile: savePath atomically: YES]; return; } if ([paramData isKindOfClass:[NSMutableArray class]]) { [paramData writeToFile: savePath atomically: YES]; } }// 读取数据从文件- (void)readDataFromFile:(NSString *)fileName toTheData:(id) paramData{ if ([paramData isKindOfClass:[NSMutableDictionary class]]) { NSMutableDictionary* tmp = [[NSMutableDictionary alloc] initWithContentsOfFile:[self dataFilePath:fileName]]; if (tmp&& tmp.count>0) { [paramData addEntriesFromDictionary:tmp]; } return; } if ([paramData isKindOfClass:[NSMutableArray class]]) { NSMutableArray *tmp=[[NSMutableArray alloc] initWithContentsOfFile:[self dataFilePath:fileName]]; if (tmp&& tmp.count>0) { [paramData addObjectsFromArray:tmp]; } return; }}- (void)applicationWillResignActive:(UIApplication *)application{ // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state. // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.}- (void)applicationDidEnterBackground:(UIApplication *)application{ // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.}- (void)applicationWillEnterForeground:(UIApplication *)application{ // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.}- (void)applicationDidBecomeActive:(UIApplication *)application{ // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.}- (void)applicationWillTerminate:(UIApplication *)application{ // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.}@end