CountDown Timer ios教程？ [英] CountDown Timer ios tutorial?

问题描述

我正在进行考试的应用程序，所以当考试开始时，时间应该从那开始。例如30分钟它应该像29:59一样减少。

I'm making an application where the exams is going on, so when exam start the, time should start with that. For example 30 minutes and it should reduce like 29:59.

我如何实现这个？

可以有谁请给我一个示例或一步一步的简单教程，我可以遵循？

Can anyone please give me a sample example or a easy step by step tutorial that i can follow?

推荐答案

此代码用于创建倒数计时器。

This code is used to create a countdown timer.

.h文件的代码。

@interface UIMyContoller : UIViewController {

NSTimer *timer;
    IBOutlet UILabel *myCounterLabel;
}

@property (nonatomic, retain) UILabel *myCounterLabel;

-(void)updateCounter:(NSTimer *)theTimer;
-(void)countdownTimer;

@end

.m文件的代码。

@implementation UIMyController
@synthesize myCounterLabel;

int hours, minutes, seconds;
int secondsLeft;

- (void)viewDidLoad {
    [super viewDidLoad];

    secondsLeft = 16925;
    [self countdownTimer];
}

- (void)updateCounter:(NSTimer *)theTimer {
    if(secondsLeft > 0 ) {
        secondsLeft -- ;
        hours = secondsLeft / 3600;
        minutes = (secondsLeft % 3600) / 60;
        seconds = (secondsLeft %3600) % 60;
        myCounterLabel.text = [NSString stringWithFormat:@"%02d:%02d:%02d", hours, minutes, seconds];
    } else {
        secondsLeft = 16925;
    }
}

-(void)countdownTimer {

    secondsLeft = hours = minutes = seconds = 0;
    if([timer isValid]) {
        [timer release];
    }
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];  
    timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateCounter:) userInfo:nil repeats:YES];
    [pool release];
}

希望这能帮到你。

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