iphone - 显示计时器，从日期开始计算天、小时、分钟和秒，然后实时递增

Question

我正在尝试显示一个计时器，该计时器从日期开始计算天数、小时、分钟和秒，然后在视图/页面上实时递增。

最好的方法是什么？

Answer 1

最好的方法是阅读日期和时间编程指南以了解如何使用NSDate、NSCalendar和NSDateComponents类。

Answer 2

你可以这样做： -

- (void)viewWillAppear:(BOOL)animated 
    {
        [self start];
        [super viewWillAppear:YES];
    }

int currentTime;
- (IBAction)start{

     currentTime = 0;
     lbl=[[UILabel alloc]init];
    //creates and fires timer every second
    myTimer = [[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(showTime) userInfo:nil repeats:YES]retain];
}
- (IBAction)stop{
    [myTimer invalidate];
    myTimer = nil;
}

- (IBAction)reset{

    [myTimer invalidate];
    lbl.text = @"00:00:00";
}

-(void)showTime{

    currentTime++; //= [lbl.text intValue];
    //int new = currentTime++;

   int secs = currentTime % 60;
int mins = (currentTime / 60) % 60;
int hour = (currentTime / 3600);
int day =   currentTime / (60 * 60 * 24);

lbl.text = [NSString stringWithFormat:@"%.2d:%.2d:%.2d:%.2d",day,hour, mins, secs];

NSLog(@"my lable == %@",lbl.text);

    NSLog(@"my lable == %@",lbl.text);
}