制作倒数计时器并在后台运行

Question

I want to add a mute button to my app that when the user clicks it, he chooses a duration of the mute and while the mute is enabled the user won't get notifications from my app.

I thought NSTimer is a good option, but how can I make a timer with it? And how can I set that the timer will run in the background aswell?

Note: I'm using location monitoring in the background.

Answer 1

I don't think you need a running timer in the background - or any complicated solution:

• Use a timer when your app is in the foreground (as usual). Cancel the mute mode when it fires.

• When your app switches to the background mode and the timer is active, cancel the timer or let it running, depending on your needs.

• Optionally, when your app is executing in background mode, just don't send notifications.

• If your app becomes suspended shortly after, your code wouldn't execute anyway.

• If your app still needs to obey the mute state when it switches to the foreground, calculate the duration of the date-time value which you stored when the mute mode has been activated and the current date-time and compare this with your timeout.

Answer 2

NSTimer can fire a method after a certain time interval

First declare a NSTimer object, say "timer"

self.timer=[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(targetMethod:) userInfo:nil repeats:YES];

Now this timer will fire the targetMethod after every 1 sec. Time interval is 1 sec. Now define the target method

- (void) targetMethod: (NSTimer*)theTimer
{
    second++;

    if(second==60)
    {
        minute++;
        second=0;

    }
}

I declared two int variable for minute and second count. Now after every 1 sec the second will increase, and after every 60 sec, minute will increase. You can try it.