我有一个 NSTimer,我希望它在 45 分钟后停止,但它不会停止。 我做错了什么?
TIMER_COUNT = 45
HOURS_IN_HOURS = 60
HOURS_IN_DAY = 24
- (void)start
{
self.timerCountdown = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateCountdown) userInfo:nil repeats: YES];
}
- (void)stop
{
[self.timerCountdown invalidate];
self.timerCountdown = nil;
}
- (void)updateCountdown
{
NSDate *currentDate = [NSDate date];
NSDate *finalTime = [currentDate dateByAddingTimeInterval:(TIMER_COUNT * HOURS_IN_HOUR)];
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *componentsHours = [calendar components:NSHourCalendarUnit fromDate:currentDate];
NSDateComponents *componentMinuts = [calendar components:NSMinuteCalendarUnit fromDate:currentDate];
NSDateComponents *componentSeconds = [calendar components:NSSecondCalendarUnit fromDate:currentDate];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *componentsDaysDiff = [gregorianCalendar components:NSDayCalendarUnit
fromDate:currentDate
toDate:finalTime
options:0];
NSLog(@"%20d Days, %02d Hours, %02d Minutes, %02d Seconds.", componentsDaysDiff.day, HOURS_IN_DAY - componentsHours.hour, HOURS_IN_HOUR - componentMinuts.minute, HOURS_IN_HOUR - componentSeconds.second);
if ([currentDate compare:finalTime] == NSOrderedSame)
{
NSLog(@"Done.");
[self stop];
}
}
提前致谢。
最佳答案
因为您的 currentDate
会在您的计时器每次计时时保持设置。每次 updateCountdown
方法运行时,[NSDate date]
都会将 currentDate
设置为当前时间。因此 finalTime
总是比 currentDate
早 45 分钟。您应该创建一个 startDate
属性并将其设置在 start
方法中:
- (void)start
{
self.timerCountdown = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateCountdown) userInfo:nil repeats: YES];
self.startDate = [NSDate date];
}
然后检查 updateCountdown
方法中的属性:
if ([self.startDate compare:finalTime] == NSOrderedSame)
{
NSLog(@"Done.");
[self stop];
}
或者,您可以使用一个整数来表示您期望的滴答数,然后每次计时器滴答时从该整数中减去一个。 像这样:
- (void)start
{
self.timerCountdown = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateCountdown) userInfo:nil repeats:YES];
self.countdown = TIMER_COUNT * HOURS_IN_HOUR;
}
- (void)updateCountdown
{
self.countdown--;
//your code
if (self.countdown == 0)
{
NSLog(@"Done.");
[self stop];
}
}
关于ios - 45 分钟后计时器不会停止,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19510565/