ios - 如何将时间添加到 iOS 项目的倒数计时器

Question

我有一个使用倒数计时器的游戏，当计时器到时，您会看到游戏概览。我想添加一个功能，如果他们点击一个按钮，它会为计时器增加 1、2 或 3 秒。我已经有了计时器的代码（如下），但我只需要知道如何为计数器添加更多时间。我想到了，我不得不说视图何时切换，并且需要计算增加的时间。

代码：

-(IBAction)Ready:(id)sender {
    [self performSelector:@selector(TimerDelay) withObject:nil afterDelay:1.0];
    [self performSelector:@selector(delay) withObject:nil afterDelay:36.5];
}

-(void)TimerDelay {
    MainInt = 36;

    timer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                         target:self
                                       selector:@selector(countDownDuration)
                                       userInfo:nil
                                        repeats:YES];
    if (timer == 0)
    {
        [timer invalidate];
    }
}

-(void)countDownDuration {
    MainInt -= 1;

    seconds.text = [NSString stringWithFormat:@"%i", MainInt];
}

-(void)delay {

    GameOverView1_4inch *second= [self.storyboard instantiateViewControllerWithIdentifier:@"GameOverView1"];
    second.finalScore = self.currentScore;
    [self presentViewController:second animated:YES completion:nil];
}

score 1 · Accepted Answer

If you're using a timer to manage the game, using a perform selector at the same time (to end the game or anything else) kind of defeats the point and makes the management very complex. Choose one route and stick with it.

When the timer is running, you can change it's fire date using setFireDate:. So, you could get the current fire date, add your time to it and then set the new fire date:

- (void)extendByTime:(NSInteger)seconds
{
    NSDate *newFireDate = [[self.timer fireDate] dateByAddingTimeInterval:seconds];
    [self.timer setFireDate:newFireDate];
}

Then, your button callbacks are something like:

- (void)buttonOnePressed:(id)sender
{
    [self extendByTime:1];
}

- (void)buttonFivePressed:(id)sender
{
    [self extendByTime:5];
}

Once you've removed the performSelector which calls delay your game end will be defined by MainInt reaching zero.

As an aside, don't do this:

if (timer == 0)

The correct approach is:

if (timer == nil)

And if the timer is nil, there's no point in trying to invalidate it...

Also a good idea to take a look at the Objective-C naming guidelines.

Based on your recent comment, it seems that you actually want the timer to continue counting at a second interval, but to add time only to the number of seconds remaining. That's even easier and doesn't require any change to the timer fire date.

- (void)extendByTime:(NSInteger)seconds {
    MainInt += seconds;
    seconds.text = [NSString stringWithFormat:@"%i", MainInt];
}

And you need to add a check in 'countDownDuration':

if (MainInt <= 0) {
    [timer invalidate];
    [self delay];
}

To determine when you're done.

score 0 · Accepted Answer

You can keep reference of the time you start the timer. Then, when you want to add extra time, calculate how much time has passed since the timer started, invalidate the timer and create a new one passing as time interval the difference between the time left of the previous timer and the extra seconds.

score 0 · Accepted Answer

嗨，尝试使用这个：

把它放在-(void)viewDidLoad方法中

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self
                                                   selector:@selector(countDownTimer) userInfo:nil repeats:YES];

然后创建-(void)countDownTimer方法

- (void)countDownTimer {
    // my method which returns the differences between two dates in my case
    double diff = [self getDateDifference];

    double days     = trunc(diff / (60 * 60 * 24));
    double seconds  = fmod(diff, 60.0);
    double minutes  = fmod(trunc(diff / 60.0), 60.0);
    double hours    = fmodf(trunc(diff / 3600.0), 24);

    if(diff > 0) {
        NSString *countDownString = [NSString stringWithFormat:@"%02.0f day(s)\n%02.0f:%02.0f:%02.0f",
                           days, hours, minutes, seconds];
        // IBOutlet label, added in .h
        self.labelCountDown.text= countDownString;
    } else {
        // stoping the timer
        [timer invalidate];
        timer = nil;
        // do something after countdown ...
    }
}

你可以添加一个- (double)getDateDifference方法，它在我的情况下返回两个日期之间的差异

- (double)getDateDifference {
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    NSDate *dateFromString = [[NSDate alloc] init];
    NSDate *now = [NSDate date];
    NSString *myDateString = @"2013-10-10 10:10:10"; // my initial date with time
    // if you want to use only time, than delete the 
    // date in myDateString and setDateFormat:@"HH:mm:ss"

    // this line is not required, I used it, because I need GMT+2
    [dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:+2]];

    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

    // get the date
    dateFromString = [dateFormatter dateFromString:myDateString];

    // this line is also not required, I used it because I need GMT+2
    // so I added two hours in seconds to 'now'
    now = [now dateByAddingTimeInterval:60*60*2];

    // getting the difference
    double diff = [dateFromString timeIntervalSinceDate:now];

    NSLog(@"dateString: %@", dateString);
    NSLog(@"now: %@", now);
    NSLog(@"targetDate: %@", dateFromString);
    NSLog(@"diff: %f", diff);

   return diff;
}

输出与此类似

dateString: 2013-10-10 00:20:00
now: 2013-10-10 00:20:00 +0000
target: 2013-10-10 00:20:28 +0000
diff: 28.382786

我希望它有帮助

score 0 · Accepted Answer

0

这是您可以使用的库。

https://github.com/akmarinov/AMClock

于 2013-10-10T12:00:40.243 回答

ios - 如何将时间添加到 iOS 项目的倒数计时器

4 回答 4

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