UIApplication的作用:

1.在应用程序图标上面添加数字

1)获取UIApplication单例

UIApplication *app = [UIApplication sharedApplication];

2)注册通知

UIUserNotificationSettings *setting = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil];

[app registerUserNotificationSettings:setting];

3)设置应用程序图标提醒数字

app.applicationIconBadgeNumber = 10;

2.设置连网状态

//获取应用程序UIApplication单例

UIApplication *app =[UIApplication sharedApplication];

//网络工作活动表示可见

app.networkActivityIndicatorVisible = YES;

3.打开URL

UIApplication *app = [UIApplication sharedApplication];

NSURL *url = [NSURL URLWithString:@"http://192.168.21.33:81"];

[app openURL:url];

4.设置状态栏