在iPhone SDK 3.0中注册通知

Question

在iPhone SDK 3.0中,我想注册一个通知,该通知会在达到特定时间时提醒我的应用程序.可能吗？谢谢

Answer 1

设置NSTimer一个每30秒运行一个选择器(或您需要的任何粒度):

 [NSTimer scheduledTimerWithTimeInterval:30.0 target:self selector:@selector(timerFired:) userInfo:nil repeats:YES];

该-timerFired:选择器(方法)将运行每隔30秒,检查时,分和第二组分,发射的通知,如果元素匹配所需时间:

 - (void) timerFired:(NSNotification *)notification {
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSCalendarUnit unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
    NSDate *date = [NSDate date];
    NSDateComponents *dateComponents = [calendar components:unitFlags fromDate:date];
    NSInteger hour =  [dateComponents hour];
    NSInteger min =   [dateComponents minute];
    NSInteger sec =   [dateComponents second];
    if ((hour == kDesiredHour) && (min == kDesiredMinute) && (sec == kDesiredSecond)) {
       [[NSNotificationCenter defaultCenter] postNotificationName:@"kTimeComponentsWereMatched" object:nil userInfo:nil];
    }
 }

您注册在某处的某个其他类中侦听此通知:

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(doSomething:) name:@"kTimeComponentsWereMatched" object:nil];

因此,你在同一个类中有一个方法可以做一些有趣的事情:

 - (void) doSomething:(NSNotification *)notification {
    // do something interesting here...
 }

如果它在一个类中,则可以合并此代码.或指定target的NSTimer指向要运行的类的实例selector英寸