即时改变badgeValue的值（使用KVO）

最新推荐文章于 2020-05-09 15:10:31 发布

佯加酱

最新推荐文章于 2020-05-09 15:10:31 发布

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分类专栏： IOS

本文链接：https://blog.youkuaiyun.com/ycw343465134/article/details/38819963

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本文介绍了一个使用Objective-C编写的iOS应用程序示例，通过UITabBarController实现多视图导航，并利用KVC观察者模式更新TabBar徽标值。

首先先创建一个类

Number

@interface Number : NSObject
{
NSNumber *badgeValue_number; //属性
}
@end

YcwAppDelegate.h文件内

@property (retain, nonatomic)Number *ycwNumber;

YcwAppDelegate.m文件内

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen]bounds]];

    YcwViewController *view = [[YcwViewController alloc]initWithNibName:@"YcwViewController" bundle:nil];
    YcwSecondViewController *secondView = [[YcwSecondViewController alloc]initWithNibName:@"YcwSecondViewController" bundle:nil];

    YcwThirdViewController *thirdView = [[YcwThirdViewController alloc]initWithNibName:@"YcwThirdViewController" bundle:nil];
    NSArray *array_controllers =[NSArray arrayWithObjects:view,secondView,thirdView, nil];

    UITabBarController *tabBarController = [[UITabBarController alloc]init];
    tabBarController.viewControllers = array_controllers;

    self.window.rootViewController = tabBarController;

    [self.window makeKeyAndVisible];


    self.ycwNumber = [[Number alloc]init];

    return YES;
}

创建一个视图YcwViewController 添加一个button事件

创建一个视图YcwThirdViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        self.tabBarItem.title = @"third";
        self.tabBarItem.image = [UIImage imageNamed:@"333.png"];

    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    delegate = [[UIApplication sharedApplication]delegate];
    [delegate.ycwNumber addObserver:self forKeyPath:@"badgeValue_number" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:NULL];

}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{


    if ([keyPath isEqualToString:@"badgeValue_number"]) {
        self.tabBarItem.badgeValue = [NSString stringWithFormat:@"%@",[delegate.ycwNumber valueForKey:@"badgeValue_number"]];

    }


}