iOS present AlertController时崩溃。 'Application tried to present modally an active controller .'

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present modally an active controller <HKConnectViewController: 0x1050158e0>.'

 

分析：

很有可能是你的触发事件中，触发了多次。也就是说：不止一次调用了present。

解决办法：

保证只执行一次

    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        [self presentViewController:self.bluetoothCloseAlertC animated:YES completion:nil];
    });