Use NotificationCenter for Cybozu Garoon3 schedules.

AppDelegate.h

// AppDelegate.h

#import <Cocoa/Cocoa.h>

@interface AppDelegate : NSObject <NSApplicationDelegate, NSUserNotificationCenterDelegate>
// Windowはいらないのでxibファイルから消しておく
@property (assign) IBOutlet NSWindow *window;
@end

AppDelegate.m

// AppDelegate.m

#define DATA_FILE_PATH @"/Users/hagino3000/tmp/data.json"
#define CHECK_INTERVAL 20 * 60

#import "AppDelegate.h"

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    [NSUserNotificationCenter defaultUserNotificationCenter].delegate = self;
  
    // 初回起動
    [self checkSchedule];
    // 次回以降はタイマーで起動
    [NSTimer scheduledTimerWithTimeInterval:CHECK_INTERVAL
                                     target:self
                                   selector:@selector(checkSchedule)
                                   userInfo:nil
                                    repeats:YES];
}

- (void)checkSchedule {

    // ファイルでスケジュールデータを受けとる
    NSInputStream* stream = [NSInputStream inputStreamWithFileAtPath:DATA_FILE_PATH];
    [stream open];
    NSError *error;
    NSArray *arr = [NSJSONSerialization JSONObjectWithStream:stream
                                                     options:NSJSONReadingMutableContainers
                                                       error:&error];
    [stream close];

    for (int i = 0; i < arr.count; i++) {
        NSDictionary *dict = [arr objectAtIndex:i];
        [self sendNotification:[dict objectForKey:@"title"]
                      subtitle:[dict objectForKey:@"time"]
                          body:[dict objectForKey:@"body"]
                           url:[dict objectForKey:@"url"]];
    }
}

- (void)sendNotification:(NSString *)title subtitle:(NSString *)subtitle body:(NSString *)body url:(NSString *)url {
  
    // UserNotificationの生成
    NSUserNotification *userNotification = [[NSUserNotification alloc] init];
    userNotification.actionButtonTitle = @"開く";
    userNotification.title = title;
    userNotification.subtitle = subtitle;
    userNotification.informativeText = body;
    userNotification.userInfo = [[NSDictionary alloc] initWithObjectsAndKeys:url, @"url", nil];

    // 通知センターに送る
    [[NSUserNotificationCenter defaultUserNotificationCenter] deliverNotification:userNotification];
    NSLog(@"done!!");
}

- (void)userNotificationCenter:(NSUserNotificationCenter *)center didActivateNotification:(NSUserNotification *)notification {

    // アクションボタンがクリックされたら、スケジュールのページを開く
    NSURL *url = [NSURL URLWithString:[notification.userInfo valueForKey:@"url"]];
    [[NSWorkspace sharedWorkspace] openURL:url];
}

@end