IOS开发—IOS 8 中设置applicationIconBadgeNumber和消息推送

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];
}

如果是注册消息推送的话，需要这样写：

float version = [[[UIDevice currentDevice] systemVersion] floatValue];

if (version >= 8.0) {
UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil];
[[UIApplication sharedApplication] registerUserNotificationSettings:settings];
[application registerForRemoteNotifications];
}