iphone - 在 Objective-c 中实现倒数计时器？

Question

我是 iOS 编程新手。我正在研究单词匹配游戏。在这个游戏中，我需要实现显示分钟和秒的时间计数器。我希望当我的游戏开始时，我的计时器从 3 分钟开始。现在我想以秒为单位反向减少这个计时器。我的代码只工作了几秒钟..这是我的代码:

  secondsLeft--;

  int seconds = (secondsLeft %3600) % 60;

  Timerlbl.text = [NSString stringWithFormat:@"%02d",seconds];


  if (seconds==0)

{


 UIAlertView *pAlert = [[UIAlertView alloc]initWithTitle:@"Sorry!!"   
 message:@"TimeOver"        delegate:self    cancelButtonTitle:@"OK"   
 otherButtonTitles:@"Cancel",nil];

 [pAlert show];

[pAlert release];

 }

 }

在 Viewdidload 中我通过计时器调用它..

          countDown=[NSTimer scheduledTimerWithTimeInterval:5.0 target:self 
                 selector:@selector(TimeOver) userInfo:nil repeats:YES];

请任何人指导我如何在几分钟和几秒钟内完成。

Answer 1

你可以这样做(启用 ARC):-

@interface ViewController()
{
UILabel *progress;
    NSTimer *timer;
    int currMinute;
    int currSeconds;
}
@end


@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
    progress=[[UILabel alloc] initWithFrame:CGRectMake(80, 15, 100, 50)];
    progress.textColor=[UIColor redColor];
    [progress setText:@"Time : 3:00"];
    progress.backgroundColor=[UIColor clearColor];
    [self.view addSubview:progress];
    currMinute=3;
    currSeconds=00;

    // Do any additional setup after loading the view, typically from a nib.
}
-(void)start
{
    timer=[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerFired) userInfo:nil repeats:YES];

}
-(void)timerFired
{
if((currMinute>0 || currSeconds>=0) && currMinute>=0)
{
    if(currSeconds==0)
    {
        currMinute-=1;
        currSeconds=59;
    }
    else if(currSeconds>0)
    {
        currSeconds-=1;
    }
    if(currMinute>-1)
    [progress setText:[NSString stringWithFormat:@"%@%d%@%02d",@"Time : ",currMinute,@":",currSeconds]];
}
    else
    {
        [timer invalidate];
    }
}