自己在學習過程中用到過NSTimer，當時在網上找了不少資料。現在自己做一個簡單的demo跟大家分享。

我就直接在下面貼上程式碼，希望能幫到一些初學iOS的朋友。

ViewController.h：

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController{

UIButton *startButton;

UIButton *stopButton;

UILabel *timeLabel;

UILabel *detailLabel;

NSTimer *mytimer;

}

@property (nonatomic

@property (nonatomic) int myTimerecord,hour,min,scd,mscd;

@property (nonatomic) NSString *hourText,*minText,*scdText,*mscdText,*timeLabelText;

@end

ViewController.m：

#import "ViewController.h"

@interfaceViewController ()

@end

@implementation ViewController

_hour = 0;

_min = 0;

_scd =

_mscd = 0;

_myTimerecord = 0;

- (void)viewDidLoad {

    [superviewDidLoad];

detailLabel = [[UILabelalloc]initWithFrame:CGRectMake(60, 30, 200, 70)];

detailLabel.text = @"計時器";

    [detailLabelsetTextAlignment:NSTextAlignmentCenter];

    [self.viewaddSubview:detailLabel];

startButton = [[UIButtonalloc]

    [startButtonsetBackgroundColor:[UIColorblueColor]];

    [startButtonsetTitle:@"開始"forState:UIControlStateNormal];

    [startButtonaddTarget:selfaction:@selector(startBtAction) forControlEvents:UIControlEventTouchUpInside];

    [self.viewaddSubview:startButton];

stopButton = [[UIButtonalloc]initWithFrame:CGRectMake(200, 320, 60, 40)];

    [stopButtonsetBackgroundColor:[UIColorblackColor]];

    [stopButtonsetTitle:@"停止"forState:UIControlStateNormal];

    [stopButtonaddTarget:selfaction:@selector(stopBtAction) forControlEvents:UIControlEventTouchUpInside];

    [self.viewaddSubview:stopButton];

timeLabel = [[UILabelalloc]initWithFrame:CGRectMake(0, 100, 320, 120)];

    [timeLabelsetTextAlignment:NSTextAlignmentCenter];

    [timeLabelsetText:@"00  :  00  :  00  :  00"];

timeLabel.font = [UIFontboldSystemFontOfSize:32.0];

    [timeLabelsetBackgroundColor:[UIColorblackColor]];

    [timeLabelsetTextColor:[UIColorwhiteColor]];

    [self.viewaddSubview:timeLabel];

//這裡0.01表示設定時間間隔是0.01秒

mytimer = [NSTimerscheduledTimerWithTimeInterval:0.01target:selfselector:@selector(timerFired) userInfo:nilrepeats:YES];

// Do any additional setup after loading the view.

}

//根據上面的設定，這個方法每隔0.01秒執行一次

-(void)timerFired

{

if (_isOn) {

_myTimerecord++;                      //記錄累計微妙的值，根據這個值計算出相對應的秒，分鐘，小時

_hour = _myTimerecord / 360000;

_min = (_myTimerecord%360000)/6000;

_scd = (_myTimerecord%6000)/100;

_mscd = _myTimerecord%100;

    }

    [selfupdateUI];

}

-(void)startBtAction

{

if (_isOn) {

_isOn = NO;

    } else {

_isOn = YES;

    }

}

-(void)stopBtAction

{

_isOn = NO;//暫停

    [selfrealStop];

}

-(void)realStop

{

_hour = 0;

_min = 0;

_scd = 0;

_mscd = 0;

_myTimerecord = 0;

_isOn = NO;

}

//這個方法實現資料（_myTimerecord）和頁面中顯示的值是統一的

-(void)updateUI

{

if (_hour < 10) {

_hourText = [[NSStringalloc]initWithFormat:@"0%d",_hour];

    }else {

_hourText = [[NSStringalloc]initWithFormat:@"%d",_hour];

    }

if (_min < 10) {

_minText = [[NSStringalloc]initWithFormat:@"0%d",_min];

    }else {

_minText = [[NSStringalloc]initWithFormat:@"%d",_min];

    }

if (_scd < 10) {

_scdText = [[NSStringalloc]initWithFormat:@"0%d",_scd];

    }else {

_scdText = [[NSStringalloc]initWithFormat:@"%d",_scd];

    }

if (_mscd < 10) {

_mscdText = [[NSStringalloc]initWithFormat:@"0%d",_mscd];

    } else {

_mscdText = [[NSStringalloc]initWithFormat:@"%d",_mscd];

    }

_timeLabelText = [[NSStringalloc]initWithFormat:@"%@  :  %@  :  %@  :  %@",_hourText,_minText,_scdText,_mscdText];

    [timeLabelsetText:_timeLabelText];

if (_isOn) {

        [startButtonsetTitle:@"暫停"forState:UIControlStateNormal];

    }else {

        [startButtonsetTitle:@"開始"forState:UIControlStateNormal];

    }

}

@end