概述

iOS中的通知包括本地推送通知和远程推送通知，两者在iOS系统中都可以通过弹出横幅的形式来提醒用户，点击横幅会打开应用。在iOS 10及之后版本的系统中，还支持通知扩展功能（UNNotificationServiceExtension、UNNotificationContentExtension），下面就来详细介绍iOS推送通知的相关功能及操作。

一、本地推送通知

本地推送通知是由本地应用触发的，是基于时间的通知形式，一般用于闹钟定时、待办事项等提醒功能。发送本地推送通知的大体步骤如下：
（1）注册本地通知；
（2）创建本地通知相关变量，并初始化；
（3）设置处理通知的时间fireDate；
（4）设置通知的内容：通知标题、通知声音、图标数字等；
（5）设置通知传递的参数userInfo，该字典内容可自定义（可选）；
（6）添加这个本地通知到UNUserNotificationCenter。

1. 注册本地推送通知

- (void)sendLocalNotification {
    
    NSString *title = @"通知-title";
    NSString *subtitle = @"通知-subtitle";
    NSString *body = @"通知-body";
    NSInteger badge = 1;
    NSInteger timeInteval = 5;
    NSDictionary *userInfo = @{@"id": @"LOCAL_NOTIFY_SCHEDULE_ID"};
    
    if (@available(iOS 10.0, *)) {
        // 1.创建通知内容
        UNMutableNotificationContent *content = [[UNMutableNotificationContent alloc] init];
        [content setValue:@(YES) forKeyPath:@"shouldAlwaysAlertWhileAppIsForeground"];
        content.sound = [UNNotificationSound defaultSound];
        content.title = title;
        content.subtitle = subtitle;
        content.body = body;
        content.badge = @(badge);

        content.userInfo = userInfo;

        // 2.设置通知附件内容
        NSError *error = nil;
        NSString *path = [[NSBundle mainBundle] pathForResource:@"logo_img_02@2x" ofType:@"png"];
        UNNotificationAttachment *att = [UNNotificationAttachment attachmentWithIdentifier:@"att1" URL:[NSURL fileURLWithPath:path] options:nil error:&error];
        if (error) {
            NSLog(@"attachment error %@", error);
        }
        content.attachments = @[att];
        content.launchImageName = @"icon_certification_status1@2x";

        // 3.设置声音
        UNNotificationSound *sound = [UNNotificationSound soundNamed:@"sound01.wav"];// [UNNotificationSound defaultSound];
        content.sound = sound;

        // 4.触发模式
        UNTimeIntervalNotificationTrigger *trigger = [UNTimeIntervalNotificationTrigger triggerWithTimeInterval:timeInteval repeats:NO];

        // 5.设置UNNotificationRequest
        UNNotificationRequest *request = [UNNotificationRequest requestWithIdentifier:LocalNotiReqIdentifer content:content trigger:trigger];

        // 6.把通知加到UNUserNotificationCenter, 到指定触发点会被触发
        [[UNUserNotificationCenter currentNotificationCenter] addNotificationRequest:request withCompletionHandler:^(NSError * _Nullable error) {
        }];

    } else {
    
        UILocalNotification *localNotification = [[UILocalNotification alloc] init];
        
        // 1.设置触发时间（如果要立即触发，无需设置）
        localNotification.timeZone = [NSTimeZone defaultTimeZone];
        localNotification.fireDate = [NSDate dateWithTimeIntervalSinceNow:5];
        
        // 2.设置通知标题
        localNotification.alertBody = title;
        
        // 3.设置通知动作按钮的标题
        localNotification.alertAction = @"查看";
        
        // 4.设置提醒的声音
        localNotification.soundName = @"sound01.wav";// UILocalNotificationDefaultSoundName;
        
        // 5.设置通知的 传递的userInfo
        localNotification.userInfo = userInfo;
        
        // 6.在规定的日期触发通知
        [[UIApplication sharedApplication] scheduleLocalNotification:localNotification];

        // 7.立即触发一个通知
        //[[UIApplication sharedApplication] presentLocalNotificationNow:localNotification];
    }
}

2. 取消本地推送通知

- (void)cancelLocalNotificaitons {
    
    // 取消一个特定的通知
    NSArray *notificaitons = [[UIApplication sharedApplication] scheduledLocalNotifications];
    // 获取当前所有的本地通知
    if (!notificaitons || notificaitons.count <= 0) { return; }
    for (UILocalNotification *notify in notificaitons) {
        if ([[notify.userInfo objectForKey:@"id"] isEqualToString:@"LOCAL_NOTIFY_SCHEDULE_ID"]) {
            if (@available(iOS 10.0, *)) {
                [[UNUserNotificationCenter currentNotificationCenter] removePendingNotificationRequestsWithIdentifiers:@[LocalNotiReqIdentifer]];
            } else {
                [[UIApplication sharedApplication] cancelLocalNotification:notify];
            }
            break;
        }
    }
    // 取消所有的本地通知
    //[[UIApplication sharedApplication] cancelAllLocalNotifications];
}

3. AppDelegate中的回调方法

在上面的代码中我们设置了userInfo，在iOS中收到并点击通知，则会自动打开应用。但是在不同版本的iOS系统中回调方式有所差异，如下：

系统版本 < iOS 10

// 如果App已经完全退出：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions;

// 当App已经完全退出时，获取userInfo参数过程如下：
// NSDictionary *userInfoLocal = (NSDictionary *)[launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];
// NSDictionary *userInfoRemote = (NSDictionary *)[launchOptions objectForKey:UIApplicationLaunchOptionsRemoteNotificationKey];

// 如果App还在运行（前台or后台）
- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification;

系统版本 >= iOS 10

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_10_0
#pragma mark - UNUserNotificationCenterDelegate
- (void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions options))completionHandler __IOS_AVAILABLE(10.0) __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);

- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void(^)(void))completionHandler __IOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0) __TVOS_PROHIBITED;
#endif

4. 实现效果

app向用户请求推送通知权限的提示弹窗：
app处于不同状态（前台、后台、锁屏）时弹出通知的效果：

PS：

当用户拒绝授权推送通知时，app无法接收通知；（用户可以到设置->通知->相应app，手动设置通知选项）

通知的声音在代码中指定，由系统播放，时长必须在30s内，否则将被默认声音替换，并且自定义声音文件必须放到main bundle中。

本地通知有数量限制，超过一定数量（64个）将被系统忽略（数据来源于网络，具体时间间隔待验证）。

二、远程推送通知

远程推送通知是通过苹果的APNs（Apple Push Notification service）发送到app，而APNs必须先知道用户设备的令牌（device token）。在启动时，app与APNs通信并接收device token，然后将其转发到App Server，App Server将该令牌和要发送的通知消息发送至APNs。 _{PS：苹果官网APNs概述}

远程推送通知的传递过程涉及几个关键组件：

App Server
Apple推送通知服务（APNs）
用户的设备（iPhone、iPad、iTouch、Mac等）
相应的app

苹果官方提供的远程推送通知的传递示意图如下：

各关键组件之间的交互细节：

开发远程推送功能首先要设置正确的推送证书和权限，步骤如下：
1）根据工程的Bundle Identifier，在苹果开发者平台中创建同名App ID，并勾选Push Notifications服务；
2）在工程的“Capabilities”中设置Push Notifications为ON；
3）远程推送必须使用真机调试，因为模拟器无法获取得到device token。
在设置好证书和权限后，按照以下步骤开发远程推送功能：

1. 注册远程通知

// iOS 8及以上版本的远程推送通知注册
- (void)registerRemoteNotifications
{
    if (@available(iOS 10.0, *)) {
        UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
        center.delegate = self;
        [center requestAuthorizationWithOptions:(UNAuthorizationOptionBadge | UNAuthorizationOptionSound | UNAuthorizationOptionAlert | UNAuthorizationOptionCarPlay) completionHandler:^(BOOL granted, NSError *_Nullable error) {
            if (!error) {
                NSLog(@"request authorization succeeded!");
                [[UIApplication sharedApplication] registerForRemoteNotifications];
            } else {
                NSLog(@"request authorization failed!");
            }
        }];
    } else {
        UIUserNotificationType types = (UIUserNotificationTypeAlert | UIUserNotificationTypeSound | UIUserNotificationTypeBadge);
        UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:types categories:nil];
        [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
        [[UIApplication sharedApplication] registerForRemoteNotifications];
    }
}

2. App获取device token

在注册远程通知后，获取device token的回调方法：

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken;

获取device token失败的回调方法：

- (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error;

3. app将device token发送给App Server

只有苹果公司知道device token的生成算法，保证唯一，device token在app卸载后重装等情况时会变化，因此为确保device token变化后app仍然能够正常接收服务器端发送的通知，建议每次启动应用都将获取到的device token传给App Server。

4. App Server将device token和要推送的消息发送给APNs

将指定的device token和消息内容发送给APNs时，必须按照苹果官方的消息格式组织消息内容。 _{PS：远程通知消息的字段、创建远程通知消息}

消息格式： {"aps":{"alert":{"title":"通知的title","subtitle":"通知的subtitle","body":"通知的body","title-loc-key":"TITLE_LOC_KEY","title-loc-args":["t_01","t_02"],"loc-key":"LOC_KEY","loc-args":["l_01","l_02"]},"sound":"sound01.wav","badge":1,"mutable-content":1,"category": "realtime"},"msgid":"123"}

5. APNs根据device token查找相应设备，并推送消息

一般情况APNs可以根据deviceToken将消息成功推送到相应设备中，但也存在用户卸载程序等导致推送消息失败的情况，这时App Server会收到APNs返回的错误信息）。

6. AppDelegate中的回调方法

// iOS<10时，且app被完全杀死
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions;

// 注：iOS10以上如果不使用UNUserNotificationCenter时，也将走此回调方法
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo;

// 支持iOS7及以上系统
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler;

//  iOS>=10: app在前台获取到通知
- (void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions))completionHandler;

//  iOS>=10: 点击通知进入app时触发（杀死/切到后台唤起）
- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void (^)(void))completionHandler;

在AppDelegate中注册远程推送通知并解析通知数据的完整代码如下：

#import "AppDelegate.h"
#import "ViewController.h"

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_10_0
#import <UserNotifications/UserNotifications.h>
#endif

@interface AppDelegate () <UNUserNotificationCenterDelegate>

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
   
    ViewController *controller = [[ViewController alloc] init];
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:controller];
    _window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    [_window setRootViewController:nav];
    [_window makeKeyAndVisible];
    
    ////注册本地推送通知（具体操作在ViewController中）
    //[self registerLocalNotification];
    // 注册远程推送通知
    [self registerRemoteNotifications];
    
    return YES;
}

- (void)registerLocalNotification {

    if (@available(iOS 10.0, *)) {
        UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
        center.delegate = self;
        [center requestAuthorizationWithOptions:(UNAuthorizationOptionBadge | UNAuthorizationOptionSound | UNAuthorizationOptionAlert) completionHandler:^(BOOL granted, NSError * _Nullable error) {
            if (!error) {
                NSLog(@"request authorization succeeded!");
            }
        }];
    } else {
        UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeAlert | UIUserNotificationTypeBadge | UIUserNotificationTypeSound categories:nil];
        [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
    }
}


- (void)registerRemoteNotifications
{
    if (@available(iOS 10.0, *)) {
        UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
        center.delegate = self;
        [center requestAuthorizationWithOptions:(UNAuthorizationOptionBadge | UNAuthorizationOptionSound | UNAuthorizationOptionAlert | UNAuthorizationOptionCarPlay) completionHandler:^(BOOL granted, NSError *_Nullable error) {
            if (!error) {
                NSLog(@"request authorization succeeded!");
                [[UIApplication sharedApplication] registerForRemoteNotifications];
            } else {
                NSLog(@"request authorization failed!");
            }
        }];
    } else {
        UIUserNotificationType types = (UIUserNotificationTypeAlert | UIUserNotificationTypeSound | UIUserNotificationTypeBadge);
        UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:types categories:nil];
        [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
        [[UIApplication sharedApplication] registerForRemoteNotifications];
    }
}


- (void)application:(UIApplication *)application didRegisterUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings {
    
    NSLog(@"didRegisterUserNotificationSettings");
}

- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification {
    
    NSLog(@"app收到本地推送(didReceiveLocalNotification:):%@", notification.userInfo);
}

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
    
    // 获取并处理deviceToken
    NSString *token = [[deviceToken description] stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"<>"]];
    token = [token stringByReplacingOccurrencesOfString:@" " withString:@""];
    NSLog(@"DeviceToken:%@\n", token);
}

- (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error {
    
    NSLog(@"didFailToRegisterForRemoteNotificationsWithError: %@", error.description);
}

// 注：iOS10以上如果不使用UNUserNotificationCenter时，也将走此回调方法
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
    // iOS6及以下系统
    if (userInfo) {
        if ([UIApplication sharedApplication].applicationState == UIApplicationStateActive) {// app位于前台通知
            NSLog(@"app位于前台通知(didReceiveRemoteNotification:):%@", userInfo);
        } else {// 切到后台唤起
            NSLog(@"app位于后台通知(didReceiveRemoteNotification:):%@", userInfo);
        }
    }
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler NS_AVAILABLE_IOS(7_0) {
    // iOS7及以上系统
    if (userInfo) {
        if ([UIApplication sharedApplication].applicationState == UIApplicationStateActive) {
            NSLog(@"app位于前台通知(didReceiveRemoteNotification:fetchCompletionHandler:):%@", userInfo);
        } else {
            NSLog(@"app位于后台通知(didReceiveRemoteNotification:fetchCompletionHandler:):%@", userInfo);
        }
    }
    completionHandler(UIBackgroundFetchResultNewData);
}


#pragma mark - iOS>=10 中收到推送消息

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_10_0

- (void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions))completionHandler
API_AVAILABLE(ios(10.0)){
    NSDictionary * userInfo = notification.request.content.userInfo;
    if (userInfo) {
        NSLog(@"app位于前台通知(willPresentNotification:):%@", userInfo);
    }
    completionHandler(UNNotificationPresentationOptionBadge|UNNotificationPresentationOptionSound|UNNotificationPresentationOptionAlert);
}

- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void (^)(void))completionHandler
API_AVAILABLE(ios(10.0)){
    NSDictionary * userInfo = response.notification.request.content.userInfo;
    if (userInfo) {
        NSLog(@"点击通知进入App时触发(didReceiveNotificationResponse:):%@", userInfo);
    }
    completionHandler();
}

#endif


@end

7. 使用Pusher工具模拟App Server推送通知

Pusher和SmartPush等工具一样，是优秀的远程推送测试工具，工具界面如下：

Pusher的使用步骤说明：
1）选择p12格式的推送证书；
2）设置是否为测试环境（默认勾选为测试环境，由于推送证书分为测试证书和生产证书，并且苹果的APNs也分为测试和生产两套环境，因此Pusher需要手动勾选推送环境）；
3）输入device token；
4）输入符合苹果要求格式的aps字符串；
5）执行推送。

效果如下：

点击横幅打开app，在回调方法中获取到的json串如下：

PS：

要使用远程推送通知功能，需要至少启动app一次；

设备不连网，是无法注册远程推送通知的；

推送过程中aps串可在适当位置添加自定义字段，消息上限为4 KB。

三、iOS 通知扩展

iOS 10及之后的推送通知具有扩展功能，包括两个方面：

通知服务扩展（UNNotificationServiceExtension），是在收到通知后且展示通知前允许开发者做一些事情，比如添加附件、加载网络请求等。点击查看官网文档

通知内容扩展（UNNotificationContentExtension），是在展示通知时展示一个自定义的用户界面。点击查看官网文档

1. 创建UNNotificationServiceExtension和UNNotificationContentExtension：

注意：

target支持的iOS版本为10.0及以上，且当前系统支持target版本。

2. 通知服务扩展UNNotificationServiceExtension

在NotificationService.m文件中，有两个回调方法：

// 系统接到通知后，有最多30秒在这里重写通知内容（如下载附件并更新通知）
- (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent *contentToDeliver))contentHandler;
// 处理过程超时，则收到的通知直接展示出来
- (void)serviceExtensionTimeWillExpire;

在通知服务扩展中加载网络请求，代码如下：

#import "NotificationService.h"
#import <AVFoundation/AVFoundation.h>

@interface NotificationService ()

@property (nonatomic, strong) void (^contentHandler)(UNNotificationContent *contentToDeliver);
@property (nonatomic, strong) UNMutableNotificationContent *bestAttemptContent;

@end

@implementation NotificationService

- (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent * _Nonnull))contentHandler {
    self.contentHandler = contentHandler;
    self.bestAttemptContent = [request.content mutableCopy];
    
    //// Modify the notification content here...
    self.bestAttemptContent.title = [NSString stringWithFormat:@"%@ [ServiceExtension modified]", self.bestAttemptContent.title];
    
    // 设置UNNotificationAction
    UNNotificationAction * actionA  =[UNNotificationAction actionWithIdentifier:@"ActionA" title:@"A_Required" options:UNNotificationActionOptionAuthenticationRequired];
    UNNotificationAction * actionB = [UNNotificationAction actionWithIdentifier:@"ActionB" title:@"B_Destructive" options:UNNotificationActionOptionDestructive];
    UNNotificationAction * actionC = [UNNotificationAction actionWithIdentifier:@"ActionC" title:@"C_Foreground" options:UNNotificationActionOptionForeground];
    UNTextInputNotificationAction * actionD = [UNTextInputNotificationAction actionWithIdentifier:@"ActionD"
                                                                                            title:@"D_InputDestructive"
                                                                                          options:UNNotificationActionOptionDestructive
                                                                             textInputButtonTitle:@"Send"
                                                                             textInputPlaceholder:@"input some words here ..."];
    NSArray *actionArr = [[NSArray alloc] initWithObjects:actionA, actionB, actionC, actionD, nil];
    NSArray *identifierArr = [[NSArray alloc] initWithObjects:@"ActionA", @"ActionB", @"ActionC", @"ActionD", nil];
    UNNotificationCategory * notficationCategory = [UNNotificationCategory categoryWithIdentifier:@"QiShareCategoryIdentifier"
                                                                                          actions:actionArr
                                                                                intentIdentifiers:identifierArr
                                                                                          options:UNNotificationCategoryOptionCustomDismissAction];
    [[UNUserNotificationCenter currentNotificationCenter] setNotificationCategories:[NSSet setWithObject:notficationCategory]];
    
    // 设置categoryIdentifier
    self.bestAttemptContent.categoryIdentifier = @"QiShareCategoryIdentifier";
    
    // 加载网络请求
    NSDictionary *userInfo =  self.bestAttemptContent.userInfo;
    NSString *mediaUrl = userInfo[@"media"][@"url"];
    NSString *mediaType = userInfo[@"media"][@"type"];
    if (!mediaUrl.length) {
        self.contentHandler(self.bestAttemptContent);
    } else {
        [self loadAttachmentForUrlString:mediaUrl withType:mediaType completionHandle:^(UNNotificationAttachment *attach) {
            
            if (attach) {
                self.bestAttemptContent.attachments = [NSArray arrayWithObject:attach];
            }
            self.contentHandler(self.bestAttemptContent);
        }];
    }
}

- (void)loadAttachmentForUrlString:(NSString *)urlStr withType:(NSString *)type completionHandle:(void(^)(UNNotificationAttachment *attach))completionHandler
{
    __block UNNotificationAttachment *attachment = nil;
    NSURL *attachmentURL = [NSURL URLWithString:urlStr];
    NSString *fileExt = [self getfileExtWithMediaType:type];
    
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
    [[session downloadTaskWithURL:attachmentURL completionHandler:^(NSURL *temporaryFileLocation, NSURLResponse *response, NSError *error) {
        if (error) {
            NSLog(@"加载多媒体失败 %@", error.localizedDescription);
        } else {
            NSFileManager *fileManager = [NSFileManager defaultManager];
            NSURL *localURL = [NSURL fileURLWithPath:[temporaryFileLocation.path stringByAppendingString:fileExt]];
            [fileManager moveItemAtURL:temporaryFileLocation toURL:localURL error:&error];
            
            // 自定义推送UI需要
            NSMutableDictionary * dict = [self.bestAttemptContent.userInfo mutableCopy];
            [dict setObject:[NSData dataWithContentsOfURL:localURL] forKey:@"image"];
            self.bestAttemptContent.userInfo = dict;
            
            NSError *attachmentError = nil;
            attachment = [UNNotificationAttachment attachmentWithIdentifier:@"QiShareCategoryIdentifier" URL:localURL options:nil error:&attachmentError];
            if (attachmentError) {
                NSLog(@"%@", attachmentError.localizedDescription);
            }
        }
        completionHandler(attachment);
    }] resume];
}

- (NSString *)getfileExtWithMediaType:(NSString *)mediaType {
    NSString *fileExt = mediaType;
    if ([mediaType isEqualToString:@"image"]) {
        fileExt = @"jpg";
    }
    if ([mediaType isEqualToString:@"video"]) {
        fileExt = @"mp4";
    }
    if ([mediaType isEqualToString:@"audio"]) {
        fileExt = @"mp3";
    }
    return [@"." stringByAppendingString:fileExt];
}

- (void)serviceExtensionTimeWillExpire {
    // Called just before the extension will be terminated by the system.
    // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
    self.contentHandler(self.bestAttemptContent);
}

@end

消息内容格式： {"aps":{"alert":{"title":"Title...","subtitle":"Subtitle...","body":"Body..."},"sound":"default","badge": 1,"mutable-content": 1,"category": "QiShareCategoryIdentifier",},"msgid":"123","media":{"type":"image","url":"https://www.fotor.com/images2/features/photo_effects/e_bw.jpg"}}

PS：

加载并处理附件时间上限为30秒，否则，通知按系统默认形式弹出；

UNNotificationAttachment的url接收的是本地文件的url；

服务端在处理推送内容时，最好加上媒体类型字段；

aps字符串中的mutable-content字段需要设置为1；

在对NotificationService进行debug时，需要在Xcode顶栏选择编译运行的target为NotificationService，否则无法进行实时debug。

3. 通知内容扩展UNNotificationContentExtension

通知内容扩展界面NotificationViewController的结构如下：

设置actions：从NotificationViewController直接继承于ViewController，因此可以在这个类中重写相关方法，来修改界面的相关布局及样式。在这个界面展开之前，用户可以通过UNNotificationAction与相应推送通知交互，但是用户和这个通知内容扩展界面无法直接交互。
设置category：推送通知内容中的category字段，与UNNotificationContentExtension的info.plist中UNNotificationExtensionCategory字段的值要匹配，系统才能找到自定义的UI。

在aps串中直接设置category字段，例如： { "aps":{ "alert":"Testing...(0)","badge":1,"sound":"default","category":"QiShareCategoryIdentifier"}}

在NotificationService.m中设置category的值如下：

self.bestAttemptContent.categoryIdentifier = @"QiShareCategoryIdentifier";

info.plist中关于category的配置如下：

UNNotificationContentExtension协议：NotificationViewController 中生成时默认实现了。

简单的英文注释很明了：

// This will be called to send the notification to be displayed by
// the extension. If the extension is being displayed and more related
// notifications arrive (eg. more messages for the same conversation)
// the same method will be called for each new notification.
- (void)didReceiveNotification:(UNNotification *)notification；

// If implemented, the method will be called when the user taps on one
// of the notification actions. The completion handler can be called
// after handling the action to dismiss the notification and forward the
// action to the app if necessary.
- (void)didReceiveNotificationResponse:(UNNotificationResponse *)response completionHandler:(void (^)(UNNotificationContentExtensionResponseOption))completion

// Called when the user taps the play or pause button.
- (void)mediaPlay;
- (void)mediaPause;

UNNotificationAttachment：attachment支持
1）音频5M（kUTTypeWaveformAudio/kUTTypeMP3/kUTTypeMPEG4Audio/kUTTypeAudioInterchangeFileFormat）
2）图片10M（kUTTypeJPEG/kUTTypeGIF/kUTTypePNG）
3）视频50M（kUTTypeMPEG/kUTTypeMPEG2Video/kUTTypeMPEG4/kUTTypeAVIMovie）

4. 自定义内容扩展界面与内容扩展功能联合使用时，代码如下：

#import "NotificationViewController.h"
#import <UserNotifications/UserNotifications.h>
#import <UserNotificationsUI/UserNotificationsUI.h>

#define Margin      15

@interface NotificationViewController () <UNNotificationContentExtension>

@property (nonatomic, strong) UILabel *label;
@property (nonatomic, strong) UILabel *subLabel;
@property (nonatomic, strong) UIImageView *imageView;

@property (nonatomic, strong) UILabel *hintLabel;

@end

@implementation NotificationViewController

- (void)viewDidLoad {

    [super viewDidLoad];
    
    CGPoint origin = self.view.frame.origin;
    CGSize size = self.view.frame.size;
    
    self.label = [[UILabel alloc] initWithFrame:CGRectMake(Margin, Margin, size.width-Margin*2, 30)];
    self.label.autoresizingMask = UIViewAutoresizingFlexibleWidth;
    [self.view addSubview:self.label];
    
    self.subLabel = [[UILabel alloc] initWithFrame:CGRectMake(Margin, CGRectGetMaxY(self.label.frame)+10, size.width-Margin*2, 30)];
    self.subLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth;
    [self.view addSubview:self.subLabel];
    
    self.imageView = [[UIImageView alloc] initWithFrame:CGRectMake(Margin, CGRectGetMaxY(self.subLabel.frame)+10, 100, 100)];
    [self.view addSubview:self.imageView];
    
    self.hintLabel = [[UILabel alloc] initWithFrame:CGRectMake(Margin, CGRectGetMaxY(self.imageView.frame)+10, size.width-Margin*2, 20)];
    [self.hintLabel setText:@"我是hintLabel"];
    [self.hintLabel setFont:[UIFont systemFontOfSize:14]];
    [self.hintLabel setTextAlignment:NSTextAlignmentLeft];
    [self.view addSubview:self.hintLabel];
    self.view.frame = CGRectMake(origin.x, origin.y, size.width, CGRectGetMaxY(self.imageView.frame)+Margin);

    // 设置控件边框颜色
    [self.label.layer setBorderColor:[UIColor redColor].CGColor];
    [self.label.layer setBorderWidth:1.0];
    [self.subLabel.layer setBorderColor:[UIColor greenColor].CGColor];
    [self.subLabel.layer setBorderWidth:1.0];
    [self.imageView.layer setBorderWidth:2.0];
    [self.imageView.layer setBorderColor:[UIColor blueColor].CGColor];
    [self.view.layer setBorderWidth:2.0];
    [self.view.layer setBorderColor:[UIColor cyanColor].CGColor];
}

- (void)didReceiveNotification:(UNNotification *)notification {
    
    self.label.text = notification.request.content.title;
    self.subLabel.text = [NSString stringWithFormat:@"%@ [ContentExtension modified]", notification.request.content.subtitle];
    
    NSData *data = notification.request.content.userInfo[@"image"];
    UIImage *image = [UIImage imageWithData:data];
    [self.imageView setImage:image];
}

- (void)didReceiveNotificationResponse:(UNNotificationResponse *)response completionHandler:(void (^)(UNNotificationContentExtensionResponseOption))completion {
    
    [self.hintLabel setText:[NSString stringWithFormat:@"触发了%@", response.actionIdentifier]];
    if ([response.actionIdentifier isEqualToString:@"ActionA"]) {
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            completion(UNNotificationContentExtensionResponseOptionDismiss);
        });
    } else if ([response.actionIdentifier isEqualToString:@"ActionB"]) {

    } else if ([response.actionIdentifier isEqualToString:@"ActionC"]) {

    }  else if ([response.actionIdentifier isEqualToString:@"ActionD"]) {

    } else {
        completion(UNNotificationContentExtensionResponseOptionDismiss);
    }
    completion(UNNotificationContentExtensionResponseOptionDoNotDismiss);
}

@end

手机收到通知时的展示（aps串以上面第2点中提到的“消息内容格式”为例）

说明：

服务扩展target和内容扩展target在配置中所支持的系统版本要在iOS10及以上；

自定义视图的大小可以通过设置NotificationViewController的preferredContentSize大小来控制，但是用户体验稍显突兀，可以通过设置info.plist中的UNNotificationExtensionInitialContentSizeRatio属性的值来优化；

contentExtension中的info.plist中NSExtension下的NSExtensionAttributes字段下可以配置以下属性的值，UNNotificationExtensionCategory：表示自定义内容假面可以识别的category，可以为数组，也即可以为这个content绑定多个通知；UNNotificationExtensionInitialContentSizeRatio：默认的UI界面的宽高比；UNNotificationExtensionDefaultContentHidden：是否显示系统默认的标题栏和内容，可选参数；UNNotificationExtensionOverridesDefaultTitle：是否让系统采用消息的标题作为通知的标题，可选参数。

处理通知内容扩展的过程中关于identifier的设置共有五处（UNNotificationAction、UNNotificationCategory、bestAttemptContent、contentExtension中的info.plist中，aps字符串中），请区别不同identifier的作用。

两个扩展联合使用，在XCode中选择当前target，才能打断点看到相应log信息。

工程源码：https://github.com/QiShare/QiNotification