iOS开发：提醒与联系人功能实现

### iOS开发：提醒与联系人功能实现 在iOS开发中，实现提醒和联系人相关功能是常见需求。下面将详细介绍如何创建基于时间和位置的提醒，以及如何访问和设置联系人信息。 #### 1. 创建基于时间的提醒 在开发过程中，我们可以构建并运行应用程序来创建基于时间的提醒。首次运行应用并点击创建基于时间的提醒按钮时，系统会询问是否允许应用访问提醒功能。 以下是创建提醒时处理错误的代码示例： ```objc 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]; }); ``` #### 2. 创建基于位置的提醒 接下来，我们将提升难度，创建基于位置的提醒。具体步骤如下： 1. **修改`ViewController.h`文件**：添加必要的框架导入和协议声明，同时定义相关的类型和实例变量。 ```objc // // ViewController.h // Remind Me // #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 UIActivityIndicatorView *activityIndicator; @property (strong, nonatomic)EKEventStore *eventStore; - (IBAction)addTimeBasedReminder:(id)sender; - (IBAction)addLocationBasedReminder:(id)sender; - (void)handleReminderAction:(RestrictedEventStoreActionHandler)block; - (void)retrieveCurrentLocation:(RetrieveCurrentLocationHandler)block; @end ``` 2. **实现`retrieveCurrentLocation:`辅助方法**：该方法用于获取用户的当前位置。 ```objc - (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]; } ``` 3. **实现`locationManager:didUpdateLocation:`委托方法**：处理位置更新事件。 ```objc - (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(abs(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]; } } ``` 4. **实现`addLocationBasedReminder:`动作方法**：创建基于位置的提醒。 ```objc - (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; al ```