如何创建一个事件，当选定的时间(通过DatePicker)发生在iPhone

Question

我想做一个定制闹钟。所以我用了Datepicker。现在我想通过Datepicker在选定的时间发生时播放声音。

所以谁能告诉我哪些类或API的使用或任何方向作出?我应该如何使我所选择的时间与系统时间匹配，以创建一个事件。我知道怎么演奏。休息对我来说是个大问号。如有任何帮助，我将不胜感激。

直到现在我已经写了这段代码，这只是显示一个日期picker和点击按钮，它显示所选的时间。: P

代码:

**.h File**
#import <UIKit/UIKit.h>
@interface The420DudeViewController : UIViewController {
    IBOutlet UINavigationBar *titleBar;
    IBOutlet UIButton *setAlarmButton;
    IBOutlet UIDatePicker *selectTimePicker;
}
@property(nonatomic, retain) IBOutlet UINavigationBar *titleBar;
@property(nonatomic, retain) IBOutlet UIButton *setAlarmButton;
@property(nonatomic, retain) IBOutlet UIDatePicker *selectTimePicker;
-(IBAction)onTapSetAlarm;
@end

**.m file **
@implementation The420DudeViewController
@synthesize titleBar,setAlarmButton,selectTimePicker;
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];
}
-(IBAction)onTapSetAlarm
{
    NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
    [timeFormat setDateFormat:@"HH:mm a"];
    NSDate *selectedDate = [[NSDate alloc] init];
    selectedDate = [selectTimePicker date];
    NSString *theTime = [timeFormat stringFromDate:selectedDate];
    UIAlertView *alert = [[UIAlertView alloc]
                          initWithTitle:@"Time selected" message:theTime delegate:nil cancelButtonTitle:@"YES" otherButtonTitles:nil];
    [alert show];
    [alert release];
//  [timeFormat release];
//  [selectedDate release];

}
- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)dealloc {
    [super dealloc];
    [titleBar release];
    [setAlarmButton release];
    [selectTimePicker release];
}
@end

Answer 1

您应该查看UILocalNotification类-这将允许您的闹钟响起，即使在应用程序关闭/在后台:https://developer.apple.com/library/ios/documentation/iPhone/Reference/UILocalNotification_Class/UILocalNotification_Class.pdf

只需将localNotification的fireDate设置为[selectTimePicker date]，然后进行调度。