创建提醒事项

//
//  ViewController.h
//  Remind Me
//
//  Created by Hans-Eric Grönlund on 8/28/12.
//  Copyright (c) 2012 Hans-Eric Grönlund. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <EventKit/EventKit.h>
#import <CoreLocation/CoreLocation.h>

typedef void(^RestrictedEventStoreActionHandler)();
typedef void(^RetrieveCurrentLocationHandler)(CLLocation *);

@interface ViewController : UIViewController<CLLocationManagerDelegate>
{
    @private
    CLLocationManager *_locationManager;
    RetrieveCurrentLocationHandler _retrieveCurrentLocationBlock;
    int _numberOfTries;
}

@property (weak, nonatomic) IBOutlet UIButton *addTimeBasedReminderButton;
@property (weak, nonatomic) IBOutlet UIButton *addLocationBasedReminderButton;
@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *activityIndicator;
@property (strong, nonatomic)EKEventStore *eventStore;

- (IBAction)addTimeBasedReminder:(id)sender;
- (IBAction)addLocationBasedReminder:(id)sender;

- (void)handleReminderAction:(RestrictedEventStoreActionHandler)block;
- (void)retrieveCurrentLocation:(RetrieveCurrentLocationHandler)block;

@end

//
//  ViewController.m
//  Remind Me
//
//  Created by Hans-Eric Grönlund on 8/28/12.
//  Copyright (c) 2012 Hans-Eric Grönlund. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (EKEventStore *)eventStore
{
    if (_eventStore == nil)
    {
        _eventStore = [[EKEventStore alloc] init];
    }
    return _eventStore;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)handleReminderAction:(RestrictedEventStoreActionHandler)block
{
    self.addTimeBasedReminderButton.enabled = NO;
    self.addLocationBasedReminderButton.enabled = NO;
    [self.eventStore requestAccessToEntityType:EKEntityTypeReminder
                                    completion:^(BOOL granted, NSError *error)
     {
         if (granted)
         {
             block();
         }
         else
         {
             UIAlertView *notGrantedAlert = [[UIAlertView alloc] initWithTitle:@"Access Denied" message:@"Access to device's reminders has been denied for this app." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
             
             dispatch_async(dispatch_get_main_queue(), ^{
                 [notGrantedAlert show];
             });
         }
         dispatch_async(dispatch_get_main_queue(), ^{
             self.addTimeBasedReminderButton.enabled = YES;
             self.addLocationBasedReminderButton.enabled = YES;
         });
     }];
}

- (IBAction)addTimeBasedReminder:(id)sender
{
    [self.activityIndicator startAnimating];
    
    [self handleReminderAction:^()
    {
        // Create Reminder
        EKReminder *newReminder = [EKReminder reminderWithEventStore:self.eventStore];
        newReminder.title = @"Simpsons is on";
        newReminder.calendar = [self.eventStore defaultCalendarForNewReminders];
        
        // Calculate the date exactly one day from now
        NSCalendar *calendar = [NSCalendar currentCalendar];
        NSDateComponents *oneDayComponents = [[NSDateComponents alloc] init];
        oneDayComponents.day = 1;
        NSDate *nextDay = [calendar dateByAddingComponents:oneDayComponents toDate:[NSDate date] options:0];
        
        NSUInteger unitFlags = NSEraCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
        NSDateComponents *tomorrowAt6PMComponents = [calendar components:unitFlags fromDate:nextDay];
        tomorrowAt6PMComponents.hour = 18;
        tomorrowAt6PMComponents.minute = 0;
        tomorrowAt6PMComponents.second = 0;
        NSDate *nextDayAt6PM = [calendar dateFromComponents:tomorrowAt6PMComponents];

        // Create an Alarm
        EKAlarm *alarm = [EKAlarm alarmWithAbsoluteDate:nextDayAt6PM];
        [newReminder addAlarm:alarm];
        newReminder.dueDateComponents = tomorrowAt6PMComponents;

        // Save Reminder
        NSString *alertTitle;
        NSString *alertMessage;
        NSString *alertButtonTitle;
        NSError *error;
        [self.eventStore saveReminder:newReminder commit:YES error:&error];
        if (error == nil)
        {
            alertTitle = @"Information";
            alertMessage = [NSString stringWithFormat:@""%@" was added to Reminders", newReminder.title];
            alertButtonTitle = @"OK";
        }
        else
        {
            alertTitle = @"Error";
            alertMessage = [NSString stringWithFormat:@"Unable to save reminder: %@", error];
            alertButtonTitle = @"Dismiss";
        }

        dispatch_async(dispatch_get_main_queue(), ^{
            UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:alertTitle message:alertMessage delegate:nil cancelButtonTitle:alertButtonTitle otherButtonTitles:nil];
            [alertView show];
            [self.activityIndicator stopAnimating];
        });
        
    }];
}

- (void)retrieveCurrentLocation:(RetrieveCurrentLocationHandler)block
{
    if ([CLLocationManager locationServicesEnabled] == NO)
    {
        UIAlertView *locationServicesDisabledAlert = [[UIAlertView alloc] initWithTitle:@"Location Services Disabled" message:@"This feature requires location services. Enable it in the privacy settings on your device" delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil];
        [locationServicesDisabledAlert show];
        return;
    }
    
    if (_locationManager == nil)
    {
        _locationManager = [[CLLocationManager alloc] init];
        _locationManager.desiredAccuracy = kCLLocationAccuracyBest;
        _locationManager.distanceFilter = 1; // meter
        _locationManager.activityType = CLActivityTypeOther;
        _locationManager.delegate = self;
    }
    _numberOfTries = 0;
    _retrieveCurrentLocationBlock = block;
    [_locationManager startUpdatingLocation];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    // Make sure this is a recent location event
    CLLocation *lastLocation = [locations lastObject];
    NSTimeInterval eventInterval = [lastLocation.timestamp timeIntervalSinceNow];
    if(fabs(eventInterval) < 30.0)
    {
        // Make sure the event is accurate enough
        if (lastLocation.horizontalAccuracy >= 0 && lastLocation.horizontalAccuracy < 20)
        {
            [_locationManager stopUpdatingLocation];
            _retrieveCurrentLocationBlock(lastLocation);
            return;
        }
    }
    if (_numberOfTries++ == 10)
    {
        [_locationManager stopUpdatingLocation];
        UIAlertView *unableToGetLocationAlert = [[UIAlertView alloc]initWithTitle:@"Error" message:@"Unable to get the current location." delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles: nil];
        [unableToGetLocationAlert show];
    }
}

- (IBAction)addLocationBasedReminder:(id)sender
{
    [self.activityIndicator startAnimating];

    [self retrieveCurrentLocation:
     ^(CLLocation *currentLocation)
     {
         if (currentLocation != nil)
         {
             [self handleReminderAction:^()
              {
                  // Create Reminder
                  EKReminder *newReminder = [EKReminder reminderWithEventStore:self.eventStore];
                  newReminder.title = @"Buy milk!";
                  newReminder.calendar = [self.eventStore defaultCalendarForNewReminders];
                  
                  // Create Location-based Alarm
                  EKStructuredLocation *currentStructuredLocation = [EKStructuredLocation locationWithTitle:@"Current Location"];
                  currentStructuredLocation.geoLocation = currentLocation;
                  
                  EKAlarm *alarm = [[EKAlarm alloc] init];
                  alarm.structuredLocation = currentStructuredLocation;
                  alarm.proximity = EKAlarmProximityLeave;
                  
                  [newReminder addAlarm:alarm];
                  
                  // Save Reminder
                  NSString *alertTitle;
                  NSString *alertMessage;
                  NSString *alertButtonTitle;
                  NSError *error;
                  [self.eventStore saveReminder:newReminder commit:YES error:&error];
                  if (error == nil)
                  {
                      alertTitle = @"Information";
                      alertMessage = [NSString stringWithFormat:@""%@" was added to Reminders", newReminder.title];
                      alertButtonTitle = @"OK";
                  }
                  else
                  {
                      alertTitle = @"Error";
                      alertMessage = [NSString stringWithFormat:@"Unable to save reminder: %@", error];
                      alertButtonTitle = @"Dismiss";
                  }
                  
                  dispatch_async(dispatch_get_main_queue(), ^{
                      UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:alertTitle message:alertMessage delegate:nil cancelButtonTitle:alertButtonTitle otherButtonTitles:nil];
                      [alertView show];
                      [self.activityIndicator stopAnimating];
                  });
              }];
         }
     }];
}
@end

创建基于时间和基于位置的提醒事件，导入框架Event Kit与Core Location。