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保存和还原选项卡栏控制器的状态

object-state uitabbarcontroller uinavigationcontroller objective-c iphone

phunehehe · 技术社区 · 16 年前

我有一个应用程序,它有一个带有两个选项卡的uitabarcontroller,每个选项卡都有自己的导航控制器。现在,我想在用户关闭应用程序时存储它的状态,这样当用户重新启动应用程序时,它将显示与上次关闭前相同的位置。
因此,在应用程序中将终止:我已经

[NSKeyedArchiver archiveRootObject:tabBarController toFile:@"lastVisitedTab"];

然后,在applicationDidFinishLaunching中:我已经

UITabBarController *last= (UITabBarController *)[NSKeyedUnarchiver unarchiveObjectWithFile:@"lastVisitedTab"];
if (last)
    tabBarController = [last retain];

我还扩展了uiimage,使其符合nscoding。但是,这不起作用,因为状态不被保留。第一个选项卡一直处于选中状态,也不保留任何导航。
有人能告诉我怎么了吗,或者告诉我怎么做才对?

2 回复 | 直到 16 年前

Felixyz 16 年前

我认为坚持实际的对象太过分了。相反,只需保存 selectedIndex 财产(使用) [NSNumber numberWithInt: tabBar.selectedIndex] )然后读回并在启动时设置属性。也许这并不能正确回答你的问题,但它可能足以满足你想要达到的目标。

Community Mohan Dere 8 年前

我终于知道怎么做了,多亏了 Felixyz 的想法。下面是我要做的事情来存储标签,不管它们的数据是什么。如果视图加载了从URL下载的数据,则存储该URL而不是整个视图。你必须重写

- (void)encodeWithCoder:(NSCoder *)encoder
- (id)initWithCoder:(NSCoder *)decoder

在uiviewcontroller子类中,告诉视图控制器在应用程序停止之前保存适当的数据。
现在,在应用程序委托中,在退出前保存数据

- (void)applicationWillTerminate:(UIApplication *)application
    // data buffer for archiving
    NSMutableData *data = [NSMutableData data];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    // the index of selected tab
    [archiver encodeInt:tabBarController.selectedIndex forKey:@"TAB_INDEX"];
    // array of keys for each navigation controller, here I have 3 navigation controllers
    NSArray *keys = [NSArray arrayWithObjects:
                     @"NAVIGATION_CONTROLLER_1",
                     @"NAVIGATION_CONTROLLER_2",
                     @"NAVIGATION_CONTROLLER_3", nil];
    for (int i = 0; i < keys.count; i++) {
        UINavigationController *controller = [tabBarController.viewControllers objectAtIndex:i];
        NSMutableArray *subControllers = [NSMutableArray arrayWithArray:controller.viewControllers];
        // the first view controller would already be on the view controller stack and should be removed
        [subControllers removeObjectAtIndex:0];
        // for each of the navigation controllers save its view controllers, except for the first one (root)
        [archiver encodeObject:subControllers forKey:[keys objectAtIndex:i]];
    }
    [archiver finishEncoding];
    // write that out to file
    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    [data writeToFile:[documentsDirectory stringByAppendingPathComponent:@"ARCHIVE_PATH"] atomically:YES];
}

然后,当重新启动时

- (void)applicationDidFinishLaunching:(UIApplication *)application {
    // set up the tabs
    tabBarController = [[UITabBarController alloc] init];
    tabBarController.viewControllers = [NSArray arrayWithObjects:
                                        [[[UINavigationController alloc] initWithRootViewController:rootViewController1] autorelease],
                                        [[[UINavigationController alloc] initWithRootViewController:rootViewController2] autorelease],
                                        [[[UINavigationController alloc] initWithRootViewController:rootViewController3] autorelease], nil];
    // look for saved data, if any
    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSData *archive = [NSData dataWithContentsOfFile:[documentsDirectory stringByAppendingPathComponent:@"ARCHIVE_PATH"]];
    // if no data found, skip this step
    if (archive) {
        NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:archive];
        // set the tab
        tabBarController.selectedIndex = [unarchiver decodeIntForKey:@"TAB_INDEX"];
        NSArray *keys = [NSArray arrayWithObjects:
                         @"NAVIGATION_CONTROLLER_1",
                         @"NAVIGATION_CONTROLLER_2",
                         @"NAVIGATION_CONTROLLER_3", nil];
        // push view controllers up the stack
        for (int i = 0; i < keys.count; i++) {
            NSArray *controllers = [unarchiver decodeObjectForKey:[keys objectAtIndex:i]];
            for (UIViewController *controller in controllers) {
                [((UINavigationController *)[tabBarController.viewControllers objectAtIndex:i]) pushViewController:controller animated:NO];
            }
        }
    }
    // Add the tab bar controller's current view as a subview of the window
    [window addSubview:tabBarController.view];
}