app图标上的badge

1、授权

因为在IOS8中要想设置applicationIconBadgeNumber，需要用户的授权，在IOS8中，需要加上下面的代码：

UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil];
[[UIApplication sharedApplication] registerUserNotificationSettings:settings];

但是这两句如果是在IOS7的系统中运行的话就会报错，所以需要先判断IOS的版本，完整代码如下：

float version = [[[UIDevice currentDevice] systemVersion] floatValue]; 
if (version >= 8.0) { 
  UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil]; 
  [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
}

2、设置值

[UIApplication sharedApplication].applicationIconBadgeNumber = 1

Tab Bar Item 的badge

#如果你的根视图控制器就是UITabBarController
//获取根视图控制器
UITabBarController *tabController = (UITabBarController *)[UIApplication sharedApplication].delegate.window.rootViewController;
//获取  UITabBarController 指向的视图控制器
UIViewController *requiredViewController = [tabController.viewControllers objectAtIndex:index];
//获取tabBarItem
UITabBarItem *item = requiredViewController.tabBarItem;
//设置值
[item setBadgeValue:@"1"];

#如果你是UIViewController进入UITabBarController
UIViewController *rootController = self.window.rootViewController;
UITabBarController *tabController = rootController.tabBarController;
UIViewController *requiredViewController = [tabController.viewControllers objectAtIndex:1];
UITabBarItem *item = requiredViewController.tabBarItem;[item setBadgeValue:@"1"];