iOS,减少图标徽章编号

Question

我用

[[UIApplication sharedApplication] setApplicationIconBadgeNumber:[UIApplication sharedApplication].applicationIconBadgeNumber -1];

减少图标徽章计数,但实际上它已被清除.当我按下主页按钮时,徽章计数不存在.

但是,如果我尝试这样的固定值

[[UIApplication sharedApplication] setApplicationIconBadgeNumber:4];

,徽章数量与预期一致.

所以,问题是:为什么

[[UIApplication sharedApplication] setApplicationIconBadgeNumber:[UIApplication sharedApplication].applicationIconBadgeNumber -1];

不工作？

Answer 1

为什么你不只是：

NSInteger numberOfBadges = [UIApplication sharedApplication].applicationIconBadgeNumber
numberOfBadges -=1;

[[UIApplication sharedApplication] setApplicationIconBadgeNumber:numberOfBadges];