sharedApplication实用方法

显示联网状态

[UIApplication sharedApplication].networkActivityIndicatorVisible =YES;

阻止屏幕变暗进入休眠状态

[UIApplication sharedApplication].idleTimerDisabled =YES;（慎重使用本功能，因为非常耗电）

设置icon上的数字图标

if (version >= 8.0) {

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

        [[UIApplication sharedApplication] registerUserNotificationSettings:settings];

    }

[UIApplication sharedApplication].applicationIconBadgeNumber = 1;