問題描述：通過picker設定時間，到了設定好的時間鬧鐘響起，並彈出提示框，點選確定，停止播放音訊。如果設定好了鬧鐘，沒有停在該頁面，而是返回了手機主螢幕或是手機鎖屏，當到了鬧鐘設定的時間，會彈出訊息通知。（如果設定的時間是已經過去的時間，頁面不會有響應，直到設定正確的時間為止.）

效果圖如下：

          

具體程式碼如下：

NaoZhongViewController.m檔案

#import "NaoZhongViewController.h"

#import <AVFoundation/AVFoundation.h>

#define kW self.view.frame.size.width

#define kH self.view.frame.size.height

@interface NaoZhongViewController ()

{

    NSTimer * _timer;  //定時器

    AVAudioPlayer * _player;

}

@property(nonatomic, weak)UIDatePicker * picker;

@property(nonatomic,weak) UILabel * label;

@property(nonatomic,assign)NSInteger lt;

@property(nonatomic,

weak) UIButton * button;

@end

@implementation NaoZhongViewController 

- (void)viewDidLoad {

    [superviewDidLoad];

    self.title=@"鬧鐘";

self.view.backgroundColor=[UIColorwhiteColor];

    [self_loadView];

}

- (void) _loadView

{

//view

    UIView * view=[[UIView alloc]initWithFrame:CGRectMake

(0, 20+45, kW, kH)];

UIDatePicker * picker=[[UIDatePickeralloc]init];

    picker.backgroundColor=[UIColorcolorWithRed:0.1green:0.1blue:0.5alpha:0.1];

    [view addSubview:picker];

    _picker=picker;

    [self.view addSubview:view];

    UIButton * button=[[UIButton alloc]initWithFrame:CGRectMake(0, 0, 100, 50)];

    button.backgroundColor=[UIColorcolorWithRed:0.1green:0.5blue:0.8alpha:0.2];

    button.center=self.view.center;

    [button setTitle:@"確定"forState:UIControlStateNormal];

    [button setTitleColor:[UIColorredColor] forState:UIControlStateNormal];

    [button addTarget:selfaction:@selector(countTime:) forControlEvents:UIControlEventTouchUpInside];

    [button setTitle:@"確定"forState:UIControlStateSelected];

    [button setTitleColor:[UIColorgrayColor] forState:UIControlStateSelected];

    _button=button;

    [self.view addSubview:button];

    UILabel * label=[[UILabel alloc]initWithFrame:CGRectMake(20, 400, kW-40, kH-400-80)];

    label.backgroundColor=[UIColorcolorWithRed:0.2green:0.2blue:0.6alpha:0.2];

    label.text=@"00:00:00";

    label.textAlignment=NSTextAlignmentCenter;

    [label setFont:[UIFontfontWithName:nilsize:80]];

    _label=label;

    [self.view addSubview:label];

    UILabel * label1=[[UILabel alloc]initWithFrame:CGRectMake(25, 400, kW-40, 40)];

    label1.text=@"鬧鐘還剩時間：";

    [self.view addSubview: label1];

}

- (void) countTime:(UIButton *) button

{

    button.selected=!button.selected;

//求從現在到設定時間的時長秒數(有誤差)

/*

    //1970到picker的秒數

    NSTimeInterval seconds=[_picker.date timeIntervalSince1970];

    NSLog(@"%@",_picker.date);   //設定的時間

    NSLog(@"%.0f",seconds);

    //1970到現在的秒數

    NSDate * date=[[NSDate alloc]init];

    NSLog(@"%@",date);

    NSTimeInterval seconds2=[date timeIntervalSince1970];

    NSLog(@"%.0f",seconds2);

    NSLog(@"時間差是：----%.0f 秒",seconds-seconds2);

    */

//求從現在到設定時間的時長秒數（有誤差）

/*

    NSDate * date=[[NSDate alloc]init];

    NSLog(@"%@",date);

    NSTimeInterval seconds2=[_picker.date timeIntervalSinceDate:date];

    NSLog(@"%.0f",seconds2);

    NSLog(@"時間差是：----%.0f 秒",seconds2);

    */

//picker 設定的時間

    //格式

NSDateFormatter * format1=[[NSDateFormatteralloc]init];

    [format1 setDateFormat:@"hh"];

NSDateFormatter * format2=[[NSDateFormatteralloc]init];

    [format2 setDateFormat:@"mm"];

//獲取小時

    NSString * str1=[format1 stringFromDate:_picker.date];

    NSInteger temp1=[str1 integerValue];

    NSDate * date3=[[NSDate alloc]init];

    NSString * str3=[format1 stringFromDate:date3];

    NSInteger temp3=[str3 integerValue];

//獲取分鐘

    NSString * str2=[format2 stringFromDate:_picker.date];

    NSInteger temp2=[str2 integerValue];

    NSDate * date4=[[NSDate alloc]init];

    NSString * str4=[format2 stringFromDate:date4];

    NSInteger temp4=[str4 integerValue];

    NSLog(@"鬧鐘時長：%li 秒",(temp1-temp3)*60*60+(temp2-temp4)*60);

//--------------------------------------------------------------------

    NSInteger lt=(temp1-temp3)*60*60+(temp2-temp4)*60;

    _lt=lt;

    if (_lt>0 && _button.selected)

    {

        NSString * strT=[NSString stringWithFormat:@"%02i:%02i:%02i",(int)lt/3600%60,(int)lt/60%60,(int)lt%60];

        _label.text=strT;

    }

    else

    {

NSLog(@"請重新設定時間....");

        _label.text=@"00:00:00";

        return;

    }

    if(_timer==nil)

    {

//每隔0.01秒重新整理一次頁面

_timer=[NSTimerscheduledTimerWithTimeInterval:0.1target:selfselector:@selector(runAction) userInfo:nilrepeats:YES];

        [[NSRunLoopcurrentRunLoop] addTimer:_timerforMode:NSRunLoopCommonModes];

NSLog(@"開始倒計時.....");

    }

    else

    {

        [_timer invalidate];   //定時器失效

    }

}

- (void) runAction

{

    _lt--;

    if (_lt==0)

    {

        [_timer invalidate];//讓定時器失效

UIAlertView * alert=[[UIAlertViewalloc]initWithTitle:@"提示"message:@"關閉鬧鐘"delegate:nilcancelButtonTitle:@"確定"otherButtonTitles:nil];

//        [alert addButtonWithTitle:@"確定"];

        alert.delegate=self;

//        [alert clickedButtonAtIndex:0];

        [alert show];

//提示框彈出的同時，開始響鬧鐘

NSString * path=[[NSBundlemainBundle]pathForResource:@"4948.mp3"ofType:nil];

        NSURL * url=[NSURL fileURLWithPath:path];

        NSError * error;

_player=[[AVAudioPlayeralloc]initWithContentsOfURL:url error:&error];

_player.numberOfLoops=-1;    //無限迴圈  =0 一遍   =1 兩遍    =2 三遍     =負數  單曲迴圈

        _player.volume=2;          //音量

        [_player prepareToPlay];    //準備工作

//[_player stop];       //卡一下

        [_player play];    //開始播放

// 1 註冊通知

UIApplication * app=[UIApplicationsharedApplication];

NSArray * array=[app scheduledLocalNotifications];

        NSLog(@"%ld",array.count);

        for (UILocalNotification * local in array) {

            NSDictionary * dic= local.userInfo;

            if ([dic[@"name"] isEqual:@"zhangsan"]) {

                //刪除指定的通知

                [app cancelLocalNotification:local];

            }

        }

        //刪除所有通知

//    [app cancelAllLocalNotifications];

        //

//判斷是否已經註冊通知

UIUserNotificationSettings* setting= [app currentUserNotificationSettings];

//如果setting.types==UIUserNotificationTypeNone 需要註冊通知

if(setting.types==UIUserNotificationTypeNone){

UIUserNotificationSettings* newSetting= [UIUserNotificationSettingssettingsForTypes:UIUserNotificationTypeBadge|UIUserNotificationTypeSound|UIUserNotificationTypeAlertcategories:nil];

            [app registerUserNotificationSettings:newSetting];

        }else{

            [selfaddLocalNotification];

        }

    }

    NSString * str=[NSString stringWithFormat:@"%02d:%02d:%02d",(int)(self.lt)/3600%24,(int)(self.lt)/60%60,(int)(self.lt)%60];

    _label.text=str;

}

#pragma mark - 增加本地通知

- (void) addLocalNotification{

UILocalNotification * notification=[[UILocalNotificationalloc] init];

    notification.fireDate=[NSDatedateWithTimeIntervalSinceNow:0];

    notification.alertBody=@"鬧鐘響了。。。。。。";

    notification.alertAction=@"開啟鬧鐘";

    notification.repeatInterval=NSCalendarUnitSecond;

    notification.applicationIconBadgeNumber=1;

//[email protected]{@"name":@"zhangsan"};

//[email protected]"4195.mp3";

    [[UIApplicationsharedApplication] scheduleLocalNotification:notification];

}

//註冊完成後呼叫

-(void)application:(UIApplication *)application didRegisterUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings{

    [selfaddLocalNotification];

}

-(void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification{

NSLog(@"+========我接受到通知了");

}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex

{

    [_player stop];

}

@end

PS：上述小程式還有一點小bug（真真是不願再看一遍自己寫的程式碼，頭疼死了），感覺現在做的東西，遇到的問題都被硬處理掉了，完全想不到準確的解決方法~ 唉~